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Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11

Neptune CHS LNG-M User manual

Neptune

CHS

Cargo Handling Simulator

LNG-M Carrier

User’s Manual

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11

Neptune CHS LNG-M User manual

Neptune

CHS

Cargo Handling Simulator

LNG-M Carrier

User’s Manual

Steffen Hårstad Jensen (s) Terje Heierstad (s)

Department/Author Approved

2008 KONGSBERG MARITIME AS

All rights reserved

No part of this work covered by the copyright

may be reproduced or otherwise copied

without prior permission from

KONGSBERG MARITIME AS

Kongsberg Maritime

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Neptune CHS LNG-M User manual i

DOCUMENT STATUS

Issue No. Date/Year Inc. by Issue No. Date/Year Inc. by

A 18-Jan-06 ABU/beba

B 11-Sep-08 STHJ/BEBA

C 08-Apr-09 STHJ/Beba

D 7-Jan-11 STHJ/beba

CHANGE IN DOCUMENT

Issue

No.

ECO

No.

Paragraph

No.

Paragraph Heading/

Description of Change

B MP-1662 Review & Updates

C MP-1692 Review & Updates

D MP-1749 Updated according to latest revision

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ii Neptune CHS LNG-M User manual

Hazard Warnings

And Cautions

Fire

If a fire condition arises emission of toxic fumes can be

anticipated from burning insulation, printed circuit boards,

ETC.

Dangerous Voltages

This equipment is not fitted with safety interlocks and lethal

voltages are exposed when the cabinets are open. Before

removing any sub-units or component all supplies must be

switched off. No user serviceable parts inside.

Electrostatic sensitive device

Certain semi conductive devices used in this equipment are

liable to damage due to static voltage. Observe all precautions

for handling of semi conductive sensitive devices.

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Neptune CHS LNG-M User manual iii

ESD precautions

Refer service to qualified personnel. Turn power off prior to

opening any of the consoles. Whenever doing work inside the

consoles use an ESD protective wrist strap.

Whenever a printed circuit board is put aside it must be put

into an ESD protective bag or on a grounded ESD mat.

Non-conductive items such as synthetic clothing, plastic

materials, etc. must be kept clear of the working area,

otherwise they may cause damage.

Printed circuit boards must be kept in ESD protective bags at

all times during storage and transport. The bags must only be

opened by qualified personnel using ESD protective

equipment as specified in this section.

Computer system

The simulator contains general purpose computers. Running

non Kongsberg Maritime software in any of them will void the

warranty. Connecting other keyboards, mice or monitors may

also void the warranty.

Notice

The information contained in this document is subject to

change without notice. Kongsberg Maritime shall not be liable

for errors contained herein or for incidental or consequential

damages in connection with the furnishing, performance, or

use of this document.

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iv Neptune CHS LNG-M User manual

List of Abbreviations and Terms

AP Aft Peak

AIS Automatic Information System

CBM Cubic Meter

CC Chemical Carrier

CHS Cargo Handling Simulator

COW Crude Oil Washing

CT Center Tank

CTS Custody Transfer System

DO Diesel Oil

DS Dynamic Stability

DW Dead Weight

ECC Error Control Correction

FP Fore Peak

FS Free Surface

FWD Forward

Gb Giga byte

GM Gravity to Metacenter

OG Gas Oil

GZ Righting moment

HFO Heavy Fuel Oil

HMI Human-Machine Interface

Hz Hertz

IFE Institutt For Energiteknikk

IBC International Code for the Construction and the Equipment of

Ships Carrying Dangerous Chemicals in Bulk

IG Inert Gas

IGG Inert Gas Generator

IMDGC International Maritime Dangerous Goods Code

IMO International Maritime Organisation

Kb Kilo byte

LAN Local Area Net

LCG Longitudinal Center of Gravity

LEL Lower Explosion Limit

LNG/C Liquefied Natural Gas Carrier

LOA Length Over All

LPG/C Liquefied Petroleum Gas Carrier

LPP Length between the Perpendiculars

MARPOL International Convention for the Prevention of Pollution from

Ships

Mb Mega byte

MEPC Marine Environment Protection Committee

MFLOPS Million floating point operations pr.sec.

MLC Meter Liquid Column

MIPS Million Instructions pr.sec.

MSC Marine Safety Committee

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Neptune CHS LNG-M User manual v

ODM Oil Discharge Monitor (equipment)

OTISS Operator Training Simulation System

P Port

PC Product Carrier

PPM Parts Per Million

P/V Pressure/Vacuum

RAM Read Access Memory

S Starboard

SAST Special Analysis and Simulation Technology

SL.TK SLOP Tank

SOLAS International Convention for the Safety of Life at Sea

TC Tank Cleaning

UEL Upper Explosion Limit

UTC Universal Time Coordinated

VCG Vertical Center of Gravity

VLCC Very Large Crude oil Carrier

WS Work Station

WT Wing Tank

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vi Neptune CHS LNG-M User manual

TABLE OF CONTENTS

Section Page

1. GENERAL .......................................................................... 1

1.1 Simulation Philosophy ....................................................... 1

1.2 General Training Objectives ............................................... 2

1.3 Specific Training Objectives ............................................... 2

1.4 Concept Description .......................................................... 4

1.5 System Description ........................................................... 5

1.6 Simulator Configuration ..................................................... 6

1.7 Computer System ............................................................. 8

1.8 Getting started ................................................................. 9

1.9 To Start the Simulation ................................................... 10

1.10 Control Functions ............................................................ 11

1.11 Cargo Handling Simulators ............................................... 12

1.12 To Create an Initial Condition ........................................... 12

1.13 To End Simulation ........................................................... 12

1.14 Computer System ........................................................... 13

1.15 Environmental Requirements ........................................... 15

1.15.2 Alarm Section ................................................................ 17

1.15.3 Function buttons at the Operator Section ........................... 18

2. NEPTUNE INSTRUCTOR FUNCTIONALITY ................................. 23

2.1 Neptune Instructor Software Systems ............................... 23

3. FUNCTIONAL DESCRIPTION ................................................. 29

3.1 Graphic Desk-top ............................................................ 29

3.1.1 Pump Models.................................................................. 31

3.1.2 Pipe/Valve Models ........................................................... 34

3.1.3 Tank Models ................................................................... 35

3.1.4 Hull Models .................................................................... 36

3.2 Vessel Particulars ........................................................... 43

3.3 Properties of LNG............................................................ 47

3.3.1 Physical Properties, Composition and Characteristics of LNG 47

3.3.2 Variation of Boiling Point of Methane with Pressure ............. 49

3.3.3 Flammability of Gases ..................................................... 51

3.3.4 Supplementary Characteristics ......................................... 54

3.4 Description of the Ship’s Equipment and Arrangements ....... 57

3.4.1 Design Concept of the Cargo System ................................ 57

3.4.2 Cargo Containment System Principle ................................. 58

3.4.3 Membrane Cargo Containment ......................................... 60

3.4.4 Deterioration or Failure ................................................... 63

3.4.5 Description of Cargo Pumps ............................................. 67

3.4.6 Stripping/Spray Pump ..................................................... 73

3.4.7 Emergency Cargo Pump .................................................. 76

3.4.8 H/D Compressor ............................................................. 79

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3.4.9 L/D Compressor ............................................................. 81

3.4.10 Gas Heater .................................................................... 83

3.4.11 Operation of H/D heater .................................................. 84

3.4.12 Operation of L/D heater .................................................. 85

3.4.13 LNG Vaporizer ................................................................ 86

3.4.14 Operation ...................................................................... 87

3.4.15 Forcing Vaporizer ........................................................... 88

3.4.16 Operation ...................................................................... 89

3.4.17 Nitrogen Generating System ............................................ 90

3.4.18 Inert Gas Generator Plant ................................................ 93

3.4.19 Cargo Control Console (CCC) ........................................... 95

3.4.20 IMS control function ....................................................... 96

3.4.21 BVG management system ............................................... 97

3.4.22 Low duty compressor control ........................................... 98

3.4.23 Control logic .................................................................. 98

3.4.24 Forcing vaporizer control ................................................. 99

3.4.25 High duty compressor control .......................................... 99

3.4.26 Spray Pump Start/Stop .................................................. 101

3.4.27 Spray line Cooldown ...................................................... 103

3.4.28 Cargo Pump Start/Stop .................................................. 104

3.4.29 Discharging .................................................................. 107

3.4.30 Cargo Tank Temperature Control ..................................... 109

3.4.31 Cargo Tank Pressure Control ........................................... 110

3.4.32 Cargo Tank Protection System ........................................ 111

3.4.33 Description of Ballast Tanks and Ballast Pumping .............. 112

3.5 Mimic Diagrams ............................................................ 113

3.5.1 Cargo Tank Overview ..................................................... 114

3.5.2 Ballast Tank Overview .................................................... 115

3.5.3 Bunker/Consumables ..................................................... 116

3.5.4 Shear Force .................................................................. 117

3.5.5 Bending Moment ........................................................... 118

3.5.6 Deflection ..................................................................... 119

3.5.7 Stability ....................................................................... 120

3.5.8 Shore Tanks ................................................................. 121

3.5.9 Ship/Shore Connection ................................................... 122

3.5.10 Deck Lines .................................................................... 124

3.5.11 Cargo Tanks ................................................................. 125

3.5.12 Cofferdams ................................................................... 126

3.5.13 Insulation Spaces Pressure Controller .............................. 127

3.5.14 Compressor Room ......................................................... 128

3.5.15 Low Duty System .......................................................... 129

3.5.16 High Duty System ......................................................... 130

3.5.17 Vapourizers .................................................................. 131

3.5.18 Nitrogen Plant ............................................................... 132

3.5.19 Inert Generator ............................................................. 133

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3.5.20 Ballast Tanks ............................................................... 134

3.5.21 Ballast Pump Room ....................................................... 135

3.5.22 H/D & Spray Control Panel ............................................. 136

3.5.23 Cargo Control Panel ...................................................... 137

3.5.24 Fixed Gas Detection System ........................................... 138

3.5.25 CCTV CAMERA .............................................................. 139

3.5.26 Picture Directory (Load Master) ...................................... 141

3.5.27 Load Master Cargo Tank Overview .................................. 142

3.5.28 Load Master Ballast Tank Overview ................................. 143

3.5.29 Load Master Bunker/Consumables .................................. 144

3.5.30 Load Master Shear Forces .............................................. 145

3.5.31 Load Master Bending Moment ........................................ 146

3.5.32 Load Master Deflection .................................................. 147

3.5.33 Load Master Stability ..................................................... 148

3.5.34 Description of Legends .................................................. 149

4. OPERATION OF THE LNG MEMBRANE TANKER ........................ 151

4.1 Introduction ................................................................. 151

4.2 Insulation Space Tests .................................................. 152

4.2.1 In Service Tests............................................................ 152

4.2.2 Method for Checking the Effectiveness of the Barriers ....... 152

4.2.3 In Service Global Tightness Test ..................................... 153

4.3 Post Dry Dock Operation ................................................ 155

4.3.1 Insulation Space Inerting ............................................... 155

4.3.2 Drying Cargo Tanks ...................................................... 161

4.3.3 Inerting Cargo Tanks .................................................... 165

4.3.4 Gassing-up Cargo Tanks ................................................ 166

4.3.5 Cooling Down Cargo Tanks ............................................ 174

4.3.6 Spraying During Ballast Voyage ...................................... 177

4.3.7 Sloshing ...................................................................... 179

4.4 Loading ....................................................................... 180

4.4.1 Preparations for Loading ................................................ 180

4.4.2 Cargo Lines Cool Down .................................................. 182

4.4.3 To Load Cargo with Vapour Return to Shore ..................... 184

4.4.4 De-Ballasting ............................................................... 187

4.5 Loaded Voyage with Boil-Off Gas Burning ........................ 190

4.5.1 Normal Boil-Off Gas Burning .......................................... 190

4.5.2 Forced Boil-Off Gas Burning ........................................... 192

4.6 Discharging with Gas Return from Shore ......................... 196

4.6.1 Preparations for Unloading ............................................. 197

4.6.2 Liquid Line and Arm Cool down before Discharging ........... 198

4.6.3 Discharging .................................................................. 199

4.6.4 Ballasting .................................................................... 202

4.7 Pre-Dry Dock Operations ............................................... 206

4.7.1 Stripping and Line Draining ............................................ 206

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4.7.2 Tank Warm Up .............................................................. 207

4.7.3 Inerting ........................................................................ 210

4.7.4 Aeration ....................................................................... 211

4.7.5 Limiting Factors ............................................................ 213

4.7.6 Discharge Plans ............................................................. 213

4.7.7 Cargo Handling Training from the Graphic Desk-top ........... 213

4.7.8 Picture Directory General ................................................ 214

4.7.9 Picture Directory LM ...................................................... 215

4.7.10 Pump Flow .................................................................... 218

4.7.11 Ballasting ..................................................................... 219

4.7.12 Inert Gas System .......................................................... 222

4.8 Stress and Stability Calculations ...................................... 224

4.8.1 Online Calculations ........................................................ 224

4.8.2 Offline Calculations ........................................................ 227

5. APPENDIX A ................................................................. 229

5.1 Instructor Station .......................................................... 229

5.2 Student Workstation ...................................................... 229

5.3 Printer ......................................................................... 229

5.4 The Functions of the Major Facilities ................................ 230

5.4.1 Computer System .......................................................... 230

5.4.2 Instructor Workstation ................................................... 231

5.4.3 Student Workstation ...................................................... 232

5.4.4 Printer ......................................................................... 232

5.4.5 Mouse .......................................................................... 232

5.4.6 Keyboard ..................................................................... 233

5.5 Operation ..................................................................... 234

5.5.1 Function buttons & blue pages ........................................ 234

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Neptune CHS LNG-M User manual 1

1. GENERAL This documentation is limited to describing and explaining relevant aspects governed by

the requirements in the Standard for certification of Maritime Simulator Systems. This

documentation is required together with the simulator in order to maintain the type

approval.

1.1 Simulation Philosophy

Over the past years simulator training has proved to be an effective method to train cargo

handling procedures, especially where an error of judgement can endanger life,

environment and property. A dynamic real-time computerised simulator can compress

years of experience into a few weeks, and provide knowledge of the dynamic and

interactive processes typical for real cargo operations.

Proper simulator training will reduce accidents and improve efficiency, and give the

trainees the necessary experience and confidence in their job-situation.

The best way to acquire practical experience is to learn from real life on real ship, but

today the efficiency requirements do not allow for this kind of onboard education, hence

the training can be carried out on a simulator. Practising decision making in a simulator

environment where decisions and their effects are monitored, opens a unique possibility to

evaluate these effects.

The opportunity to experiment on specific problems and get answers on questions such as:

"what happens if ....?" without leading to damaging of components and resultant off hire

costs, is unique. Simulation will give an easy introduction to background theories through

the realistic operation of the simulator.

It is important that the trainees experience life-like conditions on the simulator and that the

tasks they are asked to carry out are recognised as important and relevant in their job-

situation. The trainees shall be challenged at all levels of experience in order to achieve

further expertise and confidence.

Certain training objectives can only be reached properly by means of life-like hands-on

equipment and experience.

For some training objectives it is considered that colour-graphic workstation presentation

and practice will be sufficient. The choice will depend on the abstraction level the trainees

are able to cope with, their experience and the specifics of the training objective.

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2 Neptune CHS LNG-M User manual

1.2 General Training Objectives

The Maritime Training Centre shall be able to train junior officers in basic cargo handling

operations, senior officers in emergency operations and trouble shooting, and to train

senior personnel in optimal operations during cargo handling. This will be achieved by

controlled training, leading to better understanding of the total cargo operation, as a

function of realistic simulation of a LNG carrier cargo system.

In order to fulfil these requirements the simulator shall be suitable for, but not limited to:

- basic and advanced training and education of students leading to professional

qualifications and a higher officer qualification;

- refresher and recurrent training for qualified officers;

- training officers in the operation of a LNG carrier's cargo equipment together with

the most vital auxiliary equipment;

- enabling detailed studies in the different processes of a ship's cargo system.

- training officers to localise faults and deterioration, and to clearly demonstrate the

impact of various types of faults and deterioration on the system's total efficiency;

- study of overall operational economy.

1.3 Specific Training Objectives

Dependent on background knowledge and experience of the trainee, the simulator shall at

least be capable of creating situations ensuring appropriate training in:

System familiarisation:

- tank arrangement

- pipe line arrangement

- pipe line control valves

- cargo compressors (high duty and low duty)

- pumps

- vaporizers

- instrumentation

- controls

- basic procedures

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Special operations and procedures:

- gas freeing

- gassing up

- tank atmosphere evaluation

- use of inert gas system

- use of nitrogen system and purging

- cool down of pipes and tanks

- draining and stripping

- forced vaporizations and boil off to boiler

Cargo and ballast operations:

- general provisions

- ballasting

- de-ballasting

- loading cargo

- discharging cargo

Operational problems:

- normal working conditions

- introduction of

* system faults

* malfunctions

- emergency procedures.

In addition to giving the students operational training, the LNG-M is also a tool for more

intimate theoretical studies for loading/discharging operations, such as:

- Planning the operations by using LNG-M as a load computer

- Run test conditions on the loading computer

- Studying single components

- Studying tank atmosphere

- Studying inert gas in relation to boiler load

- Monitoring the discharge cost and time

- Provide training in operations that the officers will have benefit of later on

- Shows you the results of incorrect operations without damaging the equipment

- Presents all relevant terminology and relates it to associated hardware

- Demonstrates both theoretical aspects and practical results in one and the same

room.

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1.4 Concept Description

The LNG-M is based on the simulator design- and development- system, Operator Training

Simulation System (OTISS) developed by Special Analysis and Simulation Technology

Ltd. (SAST) UK.

The Operator Human-Machine Interface (HMI) is realised using the EMULA Graphic

software Package developed by Institutt For Energiteknikk (IFE) Halden, Norway.

By the simulation of faults and deteriorations, the instructor can create a training situation

that enables the trainee to meet and overcome these problems. This training environment

will give the students experience in dealing with problems that would normally demand

years of seagoing experience.

The third part of the simulator is the instructor station which includes the "simulator

controls" for:

- Changing operational and ambient conditions

- Setting faults and deteriorations, single or in series

- Simulate leaks in cargo lines and tank bulkheads

- Resetting faults

- Logging events and alarms

- General system communication

The LNG-M is designed to train students in cargo handling operation under both normal

and abnormal conditions. It is therefore of utmost importance that the training takes place

in a realistic environment.

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1.5 System Description

As pioneers in the ship automation field, Kongsberg Maritime AS know how modern

technology has improved safety, reliability and economy on board ship.

The improvement has been immense, but it is also known that it is impossible to replace

the proficiency and know how to an experienced engineer, the man who must be present in

the right place at the right time to do things quickly and efficiently.

Kongsberg Maritime AS has designed a dynamic real-time computerised simulator which

can compress years of experience into a few weeks, and provides hands-on training.

The simulator provides the necessary information on dynamic and interactive processes as

found in a real cargo plant.

The LNG-M is designed to meet the demands for basic operational training of junior

officers, fault studies with economy and optimisation studies with the senior officers. It

enables the simulation of individual auxiliary systems (sub-system) and independent

components as well as an efficient simulated presentation of a total plant.

The Cargo Handling Simulator (CHS) includes comprehensive instructor communication

links that allow him to:

- Pre-program and store situations.

- Develop and test new training programs.

- Change operational and ambient conditions.

- Freeze current situations for discussions and clarifications with the trainees.

- Setting of single faults or automatic sequential fault.

The CHS has a layout and instrumentation typical to that of a modern vessel.

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1.6 Simulator Configuration

The CHS Simulator is implemented on a network of desktops with an Instructor Station.

When fitted the Cargo Control Consoles and -Panels are connected to the same Ethernet

via a serial link converter.

Figure 1-1 Computer Configuration

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Example of a typical room layout

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1.7 Computer System

All computers run on WINDOWS.

The instructor station will be the server

for all other computers. Together with the

student workstations it forms a complete

simulator computer system.

This concept is well proven and

extremely efficient for simulation

purposes. All new generations of cargo

handling simulators are based on this

concept.

Both the instructor- and the student

stations are based on the workstation.

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1.8 Getting started

The cargo system can be started at different operating conditions dependent on the training

objectives.

1. If not starting via the Neptune Instructor System you can continue to point 2.

2. If not already running, double-click the simulator program icon to start the program.

3. The Picture Directory window appears normally, but sometimes the Initial Condition

window starts up first. In that case jump to 5.

4. Click once inside the Picture Directory window.

5. Use Shift+F6 to display the Initial Conditions window.

6. Select one of the available conditions by clicking on it.

7. The condition is loaded and the simulator is ready for training.

Note: Initial conditions can only be changed while the simulator is in freeze.

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1.9 To Start the Simulation

The simulator will always be in Freeze mode when the simulator is started and the Initial

Condition is loaded.

1. Push F1 to start the simulation.

2. Running is displayed in the upper left corner.

3. Push Home to display the Picture Directory.

4. Push any picture name to display the corresponding process diagram.

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1.10 Control Functions

The simulator allows you to control pumps, valves, and controllers etc. as follows:

• Valves: Click to open, right-click to close (colour changes to indicate open condition).

• Valves: Some valves are adjustable. Enter an opening value in percent (colour changes

to indicate open condition).

• Pumps: Click to start, right-click to stop (colour changes to indicate running).

• Fans: In some cases there is a panel to be used for starting and stopping (colour

changes to indicate running).

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1.11 Cargo Handling Simulators

In the Picture Directory the picture number background is colour coded as follows:

• Green: Indicates processes taking place in the tank system.

• Beige: Indicates control panels, ship views and various printed diagrams.

1.12 To Create an Initial Condition

The simulation can at any time be stopped and the current situation saved for later use.

1. To freeze the simulation push F2.

2. Push Shift+F6 to display the Initial Conditions.

3. Push the Create button, select an unused button and type in a name for the new

condition.

4. Push Enter.

1.13 To End Simulation

To end the simulation and stop the simulation program do the following:

1. To end the simulation push F3.

2. Click the YES button and the simulator exits.

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1.14 Computer System

On the operator stations, the operator/student(s) can view mimic pages representing the

various simulated systems. These graphic mimic process diagrams are interactive, i.e. the

process can be both monitored and controlled.

In principle, all the graphic desktops can be configured as instructor stations. Whenever a

desktop is going to be used in part task mode, the student using it will act as his own

instructor, meaning that he will have the instructor’s privilege to start/pause the simulation.

Each individual can run the exercise at his own pace.

The following pages comprise a functional description of the main cargo handling systems

and related sub-systems. The process diagrams with corresponding information such as

temperature, flow, pressure, set points, etc. are presented on the colour graphic desktop.

Additional diagrams and information giving insight to the simulated models are available

and can be addressed by using the functional keyboard.

The Process Diagrams presented have the following colour code for pipelines:

- White: Nitrogen

- Blue: Fresh Water

- Green: Sea Water

- Grey: Inert gas

- Orange: Lube Oil

- Light blue: Steam

- Blue: Liquid Cargo and Spray lines

- Red: Vapour line and Vapour build up pressure line

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The Process Diagrams comprises a lot of green numbers with a letter in front. The letter is

used to identify the type of value the number represent. Here is the meaning of these

letters:

T: Temperature

G: Flow

P: Pressure

N: Rpm

Q: Force

I: Ampere

U: Voltage

F: Frequency

E: Electrical Power

V: Valve

L: Level

X: Position

Z: Signal/Concentration

W: Viscosity

c: Constant

d: Density

H: Heat Transfer

M: Mass

R: Pump, Fan Status

By moving your mouse over the figures, a text will pop up at the bottom of the page giving

you the tag name for this value as well as a description of the figure:

G02114 is the tag name.

3973, 26 m3/h is the value with the measuring unit

COP1 FLOW is the description of the tag.

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1.15 Environmental Requirements

Local climate conditions and the system configuration determine the requirements for

heating, ventilation and air-conditioning. The heating, ventilation and air - conditioning

system must provide air flow to keep the ambient conditions within the specified

temperature and humidity range.

- Ideal temperature: 23°C± 3°C

- Ideal relative humidity: 50% ± 10%

- Dust: Air pressure in the simulator rooms should be higher than

the pressure outside. Special demands are made on the air-

conditioning units filter if the air includes corrosive gases,

salts, conductive particles or other unusual particles of

dust.

Minimum and maximum operational requirements:

- Minimum temperature : 10°C

- Maximum temperature : 30°C

- Relative humidity : 15% to 80%

If the humidity is lower than 40%, static electricity may become a problem.

In order to ensure reliable operation of the air-conditioning unit, preventive maintenance

should be carried out regularly.

Thermostats must be installed in each room to allow temperatures to be controlled

individually.

NOTE! The Air-conditioning equipment must include an automatic restart after a

power failure.

It is necessary to maintain air-conditioning even when equipment is shut down, because

parts of the system remain energized. If the humidity specifications are not maintained,

condensation may accumulate which can cause damage to circuits when power is

reapplied.

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1.15.1.1 Running (F1)

Starts simulation after having frozen the simulation. The time starts running, and the

student(s) can proceed with the exercise. When the RUNNING button is pressed, a

message will inform that the simulation has started.

1.15.1.2 Freeze (F2)

Freezes simulation during breaks or when situation needs time-out for evaluation. When

FREEZE button is pushed, a message will inform that simulation is halted. The simulator

must be in FREEZE before loading an Initial Condition or a Scenario.

1.15.1.3 Stop (F3)

Ends simulation after a message. Pressing STOP and typing "yes" after prompt will log out

of simulator completely, and the desktop will return to the simulator model login-window.

To restart, proceed according to the following steps:

Type the user's name in the LOGIN picture (i.e. student1) and press ENTER. After a while

a new display appears, and by means of the left push button, select the LNG-M simulation

plant. A complete start up takes about 2 - 3 minutes. When finished, the instructor picture

Init Condition appears. Load the exercise wanted by pressing the middle button of the

mouse at the Init Condition, and proceed by pressing RUNNING.

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1.15.2 Alarm Section

1.15.2.1 Alarm Pages

The alarm system has several groups with a corresponding red alarm indicator numbered

from 1 through 28. Normally, all alarm lamps are turned off. As soon as an alarm occurs,

one of the alarm lamps starts flashing. Additional information is obtained by choosing the

group with the left mouse button.

Each lamp covers alarm points from dedicated sub systems. The alarm point exceeded

normal values, turns into a flashing mode.

The Alarm point (displayed in the MD picture) turns to steady condition as soon as the

operator moves the cursor to its location and resets the alarm by using the left hand side

push button of the mouse.

As appropriate actions are carried out, the alarm point previously indicated alarm

condition, turns off.

Measured values are displayed together with tag no, tag name, engineering units, and

upper/lower limits for alarms. The limits can be altered from Instructor mode by point and

click with left mouse button at limit and then type in new value, press “Enter” (Carriage

Return).

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1.15.3 Function buttons at the Operator Section

This section comprises all remedies for the student to conduct an exercise independent on

the Instructor or other students. From this section, the student has access to the

Malfunction List, Variable List, Alarm List, Picture Directory and other useful features.

The following pages contain information on how to utilise these functions.

1.15.3.1 Malfunction List (F9)

Most of the Model Drawings comprises one or more buttons marked M. By clicking at one

of these buttons with the left push-button of the mouse, a new window will appear at the

monitor containing the Malfunction List directory. (The M-buttons turn yellow when

malfunctions are activated (in Instructor mode only!)). When in operator mode (student),

all malfunctions are displayed, but there is no indication of which fault is introduced. In

instructor mode, the same window shows active malfunctions and in addition their settings.

Malfunctions are activated by the left hand side push-button of the mouse, while resetting

of malfunctions introduced is carried out by use of the right hand side push-button at the

mouse.

To rectify a suspected fault, move the cursor to the variable in the Malfunction List (ex

M1301), and press the right hand push-button of the Mouse. The response from the

computer will either be "Repair Attempt" or "Malfunction Reset". If the Malfunction log is

turned on, all attempts on repairing the fault are printed.

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1.15.3.2 Variable List (F10)

Displays a window with a list of all variables in the simulator. All related information is

organised in groups. This means that all variables from the Cargo line 1 system are located

at pages starting at 0010 until 0017. The List can be scrolled, moved or removed by using

the mouse and cursor.

After pushing VARIABLE LIST, identify sub system and press selected system. Displayed

window will then be identical to the variables found in the corresponding Model Drawing

ex. MD 02 at the monitor. Tag details and measured values will be displayed. Displayed

data can be changed after clicking on values with left mouse button. After typing in new

values and pressing enter new data is entered.

There are several ways to change the value of a model variable (ex. start/stop of pumps).

One of them is using the Variable List. (Any pump or valve can be operated from this part

of the simulator.) As the component to be operated is found, move the cursor to the

corresponding variable, press the select button at the unit and type the new value and

terminate by pressing "Enter" (Carriage Return).

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1.15.3.3 Alarm List (F11)

The Alarm List contains alarm groups displaying information of actual value, alarm limits

and alarm status. After recognition of the desired Alarm group in the Alarm group

directory, use the select button to display the desired alarm group. List can be scrolled,

moved or removed with cursor and left mouse button to find desired alarm.

After having pressed the ALARM LIST and identified the sub system, window with list of

alarms will be displayed.

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Doc.no.: SO-1295-D / 7-Jan-11


1.15.3.4 Picture Directory (Home)

Displays the directory of all Model Drawings (MD's). After recognition of system, click

with the left mouse button on the actual Model Drawing, and seconds later, the subsystem

is displayed on the screen.

1.15.3.5 Mark Picture (Shift+F7)

When pressing Mark Picture, the displayed Model drawing can be saved, and easily

recalled by using the Recall Marked Picture (F7). After clicking Mark Picture enter a

chosen number between 0 and 9. After clicking Recall Marked Picture, followed by the

same number, the previously MD is displayed again.

1.15.3.6 Select Picture (Shift+Home)

Allows selection of a Model Drawing after typing: MD and its corresponding number (in

one word). Enter MD and the MD's number without space, i.e. MD 101 and "Enter".

1.15.3.7 Previous Picture/Next Picture (PageUp/PageDown)

Allows scrolling to next/previous model drawing (ex.MD 07 MD 08 and MD 09) in line as

listed in picture directory.

1.15.3.8 Alarm Acknowledge

Acknowledges the alarm being pointed at with the cursor. Use the left mouse button.

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1.15.3.9 Alarm Log (F8)

Displays pages of all present alarms. Press the "PageUp" or “PageDown” key to get the

next page of alarms.

1.15.3.10 Alarm Silence (F12)

Resets alarm horn (where installed) in the Cargo Control Room and the internal buzzer.

1.15.3.11 Print Report

The "Print report" field is on the lower part of the VDU and by pressing this soft button a

complete printout of the alarm status is initiated.

1.15.3.12 Unit Conversion

The "Unit Conversion" field is on the lower part of the VDU and by pressing this soft

button a menu of different conversions "pops up" (Length, Volume, Area, etc.). Press one

of the soft keys in the menu. Press the middle button on the mouse and type the value of

the specific unit you want to be converted. And read the converted values in the other

fields.

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2. NEPTUNE INSTRUCTOR FUNCTIONALITY Kongsberg Maritime simulators have released for the Engine Room and Cargo Handling

Simulators the “State of the Art” Instructor, Monitoring and Assessment system.

Kongsberg in close cooperation with experienced world wide instructors, Norwegian

Maritime Directorate and Dot Norske VERITAS (DEN), have designed and developed an

Instructor, Monitoring and Assessment System that is excellent with regards to user-

friendliness and efficiency.

This chapter list available features that can be delivered along with this simulator.

2.1 Neptune Instructor Software Systems

The following will be provided:

Item Content Neptune

Instructorless

Neptune Instructorless gives instructor and students the option to

run readymade exercises, where following features are included.

Includes:

All configurations includes well proven models

Load simulation model on each station

Run simulation

Freeze simulation

Stop simulation

Load initial conditions

Create new initial conditions

Students can run the simulation independently

Insertion of malfunctions

Access to alarm list

Access to variable list.

Neptune Basic Includes:

Neptune Instructorless; as previously listed

Power-up all student stations

Recording of the complete exercise

Replay the whole exercises

Go back to any point in time for restart

-Create exercises including Initial conditions

Deploy exercises to student stations

-Centralized Run/Freeze control of all student stations

Connect student stations in clusters for team training

Send Instant Messages to student(s)

Send Instant Actions (Malfunctions or Events)

Recording of the complete exercise

Power shut-down of student stations

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Item Content Neptune

Professional

Includes:

Neptune Basic; as previously listed

Student Station (Access) Configuration

Exercise development, incl. triggers and actions

E-Coach, Electronic guidance system to students

Assessment

Item Description Instructor

Station

Classroom

View

Monitor and control the

students in the classroom (or

full mission simulator).

Instructor can tailor the view

according to site layout

Instructor

Station

Classroom

View

-Start exercises on Pac’s in the

classroom

-Run/pause exercises in the

classroom

-“Client Connect” to exercises

in the classroom

-Set up groups for team

training

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Item Description New Exercise

Structure

Exercise Structure comprises:

Initial Condition and

Scenario Modules

based on:

Triggers

E-Coach Messages

Actions

Assessment

Instructor

Controlled

configuration

for each of

the Student

Stations

Configuration of stations is

part of the exercise. It is

possible to add new stations to

an ongoing exercise “on the

fly”.

Trigger

Overview

Displays the state (Active/Not

Active) of all the triggers in

the module.

Displays users of the trigger

(other triggers, actions,

assessment and e-coach

messages)

Link to editors

Instructor control of triggers

(on the fly).

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Item Description Logic Block

Based Trigger

Editor

Building block used in e-coach

messages, actions and

assessments

Graphical editor

Flexible and powerful

Calculates output

(true/false) based on input

and logic blocks.

Configurable input

E-Coach

Overview

Displays the state (sent/ not

sent) of all e-coach messages

Link to trigger and

message editor

Possible for the instructor

to disable messages

(online).

E-Coach

Editor

Initiated by trigger

From “virtual instructor”

or other “outside world”

(e.g. Captain, VETS)

To a selected screen or all

screens.

Action and

Malfunction

Editor

Activated by trigger:

Additional triggers to

specify on/off conditions

for the criterion

Possible to select between

different types of scoring

(illustrated graphically)

Possible to define “critical”

criteria Action and

Malfunction

Editor

Malfunction introduced as

on/off. Instructor can freely

decide when and for how long

the malfunction shall be

activated

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


Item Description Action and

Malfunction

Editor

Malfunction introduced as

repeating on/ off.

Action and

Malfunction

Editor

Malfunction introduced as a

repeating sine shape, where

Amplitude and Time period is

adjustable.

Action and

Malfunction

Editor

Malfunction introduced where

intensity and duration is

randomly selected.

Assessment

Overview

Overview of all assessment

criteria

Calculates total score

Instructor can define

parameters for overall

scoring

Pass and Fail evaluation is

completely based on

objective criteria

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3. FUNCTIONAL DESCRIPTION

3.1 Graphic Desk-top

Graphic Desk-tops are available at the instructor station, trainees desk-top and in the full-

mission consoles in engine control room.

In principle the stations are identical and the functions present on each similar.

On the operator stations, the operator/student(s) can view mimic pages representing the

various simulated systems. These graphic mimic process diagrams are interactive, i.e. the

process can be both monitored and controlled.

In principle, all the graphic desk-tops can be configured as instructor stations. Whenever a

desk-top is going to be used in part task mode, the student using it will act as his own

instructor, meaning that he will have the instructor’s privilege to start/pause the simulation.

Each individual can run the exercise at his own pace.

The colours, symbols and abbreviations used in the mimic diagrams are common

throughout all pictures and are described and explained in MD 150 Description of Legends.

Models

The main element in the CHS Cargo Handling Simulator is a set of dynamic models.

The models are based on physical laws and are updated at regular intervals thereby

yielding a dynamic behaviour. The various models are linked together and replicate the

mutual interactions and dependencies that can be experienced in real life.

For overview, the models are grouped together into:

- pump modells

- pipe/valve modells

- tank modells

- Hull models

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Doc.no.: SO-1295-D / 7-Jan-11


Open Valve/Start Pump

Flowto / fromtanks

Change in:-tank content-tank level

Change in: Change in:-draught-trim-heel

-load distr.-shear force-bend. moment-hull deflection

HULLMODELS

TANKMODELS

PIPE / VALVEMODELS

PUMPMODELS

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3.1.1 Pump Models

3.1.1.1 The Centrifugal Pump

The relationship between discharge head, flow and pump speed for centrifugal pumps can

be expressed as follows:

H = k0*n2 + k1*n*q + K2*q2

Where H = discharge head (delivery pressure)

n = relative pump speed

q = relative volume flow

k0, k1 and K2 are design related constants

H

q

n1

n2n3

Flow resistance

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Model variables & constants The model variables H, n and q are currently and

dynamically updated during the simulation, while the

model constants k0, k

1 and k2 are set initially, thereby

'designing' the capacity and the performance of the

pump.

El. power The deep well pumps are hydraulically driven, which

means that electric power has to be available. This is

provided from the engine room (instructor).

Cavitation Even with deep well pumps cavitation may occur.

This happens if the pump inlet pressure, pinlet, is

getting lower than the vaporization pressure, pvap., for the actual fluid pumped. Then gas bubbles are

generated in the fluid, resulting in fluctuating pump

speed, unsteady flow and increasing bearing

temperature. The dynamic inlet pressure, pinlet, is

dependent on the static inlet pressure and the flow

velocity (Net Positive Suction Head - NPSH).

Cavitation precautions The best way to avoid cavitation conditions when the

static inlet pressure is reduced due to low liquid level

is to reduce the liquid flow rate, either by reducing

the pump speed or by throttling the pump discharge

valve.

Pvap The vaporization pressure, Pvap., will vary from fluid

to fluid. Thus the Pvap. for crude oil and refined

products will be sufficiently high to cause cavitation

problems, whilst the Pvap for ballast water will be

below any critical limit.

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Doc.no.: SO-1295-D / 7-Jan-11


3.1.1.2 The Stripping Eductor

Stripping eductors are used complementary to conventional centrifugal pumps to remove

the last parts of the liquid that remain in the tank (tank stripping).

B AC

D

Drivingflow

Suctionflow

The eductor works on the principle that the total sum of energy in a liquid flow is constant

(Bernoulli's Law).

When the liquid flows from A to B, and when it is constricted in C, a higher velocity is

gained in this point. The kinetic energy will then increase in this point, too. Because of the

fact that the total sum of energy is constant, the static energy is reduced accordingly,

yielding a lower static pressure in C. This will create a suction flow through D. Thus an

increased driving flow rate will result in a higher suction flow rate.

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


3.1.2 Pipe/Valve Models

A flow through a pipeline is caused by different pressures in the two ends (nodes) of the

pipeline. Flow is increased by increased pressure drop across the pipeline and reduced by

increased resistance in the pipeline. The resistance may be caused by reduced pipe

dimensions, bends, orifices or throttling valves.

q = cv p

where q = flow

1/cv = flow resistance

p = pressure drop

= specific density

Often the various pipelines are connected in nodes. The flow is then distributed on various

branches dependent on the actual difference in pressures and flow restrictions.

p0

q0

cv1

cv2

cv3

p1

q1

p2

q2

p3q3

q1 = cv1 p1 ; p1 = p0 - p1

q2 = cv2 p2 ; p2 = p0 - p2

q3 = cv3 p2 ; p3 = p0 - p3

q0 = q1 + q2 + q3

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3.1.3 Tank Models

3.1.3.1 Modelling Of Tank Levels

Based on tables containing the tank geometry the actual tank levels are calculated currently

from the actual contents of liquids in the tanks. The actual contents of liquids in the tanks

are based on the current flows to or from the tanks as computed by the Pipe/Valve Models.

Tank Level Gauging The tank levels are measured directly. I.e., Changing the

weight of the cargo/ballast without changing the volume (i.e.

changing the specific density) will not change the actual level.

Changing the volume without changing the total weight (e.g.

due to variations in temperature) will result in changed levels.

Sensor Location The sensors are located aft and in the centrelines of the tanks.

I.e.: The level measured are influenced by the ship's trim, but

not by the heel.

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3.1.4 Hull Models

The content of liquids in the tanks will have an inevitable impact on the hull condition in

terms of:

- hydrostatic conditions:

- draught

- trim

- heel

- intact stability

- meta centre height

- hull stress

- shear force

- bending moment

- hull deflection

3.1.4.1 Hydrostatic Conditions

Draught The draught is adjusted until the weight of the displaced water,

WD, equalizes the light ship weight, WLS, and the cargo weight,

WC.

WD = WLS + WC = *

where = specific gravity of water

= volume of displaced water

G

B dt

A W

T

When the weight of the cargo is changed the draught will be changed accordingly. The

change in draught can be estimated from the formula for displacement (Tons) Per. Cm

draught:

dWD = rAW * 0.01(Tons/Cm)

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This can be found in the tables and curve sheet for the hydrostatics.

t

W D

dWD

T

Trim Trim is adjusted until the trimming moment from the gravity forces

(light ship weight + cargo weight) equalizes the buoyancy moment

from the displaced water.

The trimming moment is calculated with the basis in the Longitudinal

Centre of Flotation (LCF) and the trimming takes place around this

point.

The location of the LCF is given by the shape and area of the hull's

water plane at the actual draught, as the total longitudinal moment of

the water plane-area is to be equal to zero at this point.

F

a

M 1

g

WL 1

WL0

S

The amount of trimming can be estimated by means of the Moment to Trim 1 Cm. formula:

MT = I L

L

This can be found in the hydrostatics tables.

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Heel The heel is adjusted until the heeling moment is equalized by the

buoyancy moment of the displaced water.

The heel will always take place along the water plane’s

longitudinal centre line.

B (x)

dx

x

LCF

L

Water - plane area

L L

AW = _ dAW = _ B(x) dx

0 0

Water - plane moment of area (longitudinal)

L L

FL = _ xdAW = _ B(x)x dx

0 0

Water moment of inertia (longitudinal)

L L

IL = _ x2dAW = _ B(x)x2 dx

0 0

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3.1.4.2 Intact Stability

As long as the vessel lies in upright position there will always be equilibrium between the

weight forces (light ship + cargo) acting through the gravity centre, G, and the total

buoyancy forces acting through the buoyancy centre, B.

G and B will always be located on the same vertical line at a distance KG and KB from the

keel respectively.

G

B

K

Ships heeling When the ship is inclined due to a heeling moment, the

buoyancy centre will move to a new position due to the

displacement's volume and shape.

Meta Centre The vertical line through B will cut the ship's centre line at an

angle, in the point M. At small angles of heeling the point M

is denoted the Initial Meta Centre.

The horizontal distance between the centre of gravity, G, and

the vertical line through the new centre of buoyancy, B', is

denoted GZ and represents the arm of righting moment.

G

B

K

B'

M

ZØ

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Meta Centre The distance between the Centre of Gravity, G, and the Meta

Height, GM Centre, M, is denoted the Meta Centre Height, GM.

Thus:

When GM > 0:

The heel will be counteracted by a righting moment.

The ship is said to be stable.

When GM = 0:

The heel will remain.

The ship is said to be indifferent.

When GM < 0:

The heel will increase.

The ship is said to be unstable.

Variable GM /

variable GZ

Hydrostatic considerations will show that the meta centre

height, GM, will decrease with increasing draught, T.

The GM will be further reduced if free surfaces occur in one

or more tanks. The change in GM will inevitably have impact

on the righting arm, GZ, which is the most relevant parameter

for the intact stability.

15 degr.

30 degr.

45 degr.

60 degr.GZ

Displacement (draught)

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3.1.4.3 Hull Stresses

Load Distribution The forces acting on a ship's hull will be the distributed

weight forces (lightship + cargo) and the distributed buoyancy

forces. As long as the ship lies still in water the sum of these

forces balances each other. However, the resulting forces may

be uneven distributed. This is particular the case during the

loading and discharging operation.

Shear Forces As a result of the uneven distribution of load along the hull,

shear forces will appear.

Mathematically, shear forces can be described as the integral

of the distributed load.

L

Q = q dL Q = shear force

0 q = distributed load

L = ships (hulls) length

Shear forces will act as vertical cutting forces onto the hull

structure and should be kept within the limits of the hull

construction's tensile strength.

Bending Moment The distributed shear forces will result in a bending moment

for the hull.

Mathematically, hull bending moment can be described as

the integral of the distributed shear forces.

L

M = Q dL M = longitudinal bending moment

0 Q = distributed shear force

L = ships (hulls) length

Longitudinal bending moment will cause strains in the hull

construction and should be kept within pre-set limits.

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The relationship between load distribution, shear forces and

bending moment is schematically shown in the figure below.

q Q

-+ +

-

M

0

q: load distribution

Q: shear force

M: bending moment

Hull deflection As the steel in the hull is elastic the longitudinal bending

moment will result in a certain deflection of the hull. The hull

deflection curve will have the same shape as the bending

moment curve.

Thermal deflection In addition to the deflection caused by the bending moment

the hull may be subjected to thermal deflection too. This is the

case in tropical waters where the sun is heating the deck and

the superstructure, while the submerged part of the hull is

cooled by the water.

In these circumstances it should be noted that the deflection

caused by the hogging moment in ballasted or unloaded

condition will be superimposed on the thermal deflection.

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3.2 Vessel Particulars

The modelling of the Cargo Handling Simulator CHS – LNG-M is based on a

vessel with double hull and double bottom.

Ships name LNG Membrane

Signal letters ZCDN9

IMO number 9266962

Port of registry HAMILTON

Flag Bermuda

Builder Ship No. 22xx, Daewoo Shipbuilding &

Marine Engineering Co, South Korea

Length overall 285,40 m

Length between perpendiculars 274,40 m

Breadth moulded 43,40 m

Depth moulded main deck 26,00 m

Draught design 11,35 m

Draught scantling 12,35 m

Service Speed at MCR with 15% S.M. 19,75 Knots

Deadweight 83067,7 MT

Gross tonnage (Int.) 97561 GT

Net tonnage (Int.) 29268 NT

Displacement 114153,4 MT

Class Lloyd’s Register of Shipping:

+100A1. Liquefied Gas Tanker. Ship type

2G. Methane in Membrane Tanks. Max

Vapour Pressure 0.25 bar,

Min.Temperature -163°, ShipRight

(SDA), *IWS, LI, +LMC, UMS, NAV1,

IBS, HCM, TCM with descriptive notes

Pt. Higher Tensile, ETA, ShipRight

(FDA, CM, BWMP(S), SCM), EP

Cargo Tank capacities:

Compartment Capacity @ 98,5 % and –163 C

Cargo Tank no 1 21628,7 m³




Total all tanks 143725,7 m³

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Ballast Tank capacities:

Capacity (m³)

F.P. tk 1355,9

FWD DEEP W.B. TK(P) 1581,8

FWD DEEP W.B. TK(S) 1581,8

FWD DEEP W.B. TK(C) 1748,6

No 1 W.B. TK (P) 5877,8

No 1 W.B. TK (S) 5877,8

No 2 W.B. TK (P) 6145,9

No 2 W.B. TK (S) 6145,9

No 3 W.B. TK (P) 6262,4

No 3 W.B. TK (S) 6262,4

No 4 W.B. TK (P) 5233,1

No 4 W.B. TK (S) 5233,1

E/R W.B. TK (P) 1025,8

E/R W.B. TK (S) 1025,8

A. P. tank 1145,8

TOTAL 56503,9

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Cargo pumps:

8 sets

Type Vert. Centrifugal submerged

Capacity 1650 m3/h x 150 mlc

Drive Electric

Stripping/Spray pumps:

5 sets



Drive Electric

Emergency Cargo pump:

1 set



Drive Electric

Vacuum pumps:

2 sets

Type Rotary vane

Capacity 1250 m3/h

Drive Electric

High duty compressor

2 sets

Type Horizontal Centrifugal

Suction capacity 18000 m3/h

Delivery condition 196 kPaA

Drive Electric

Low duty compressor

2 sets

Type Horizontal Centrifugal

Suction capacity 3000 m3/h

Delivery condition 196 kPaA

Drive Electric

High duty heater

1 sets

Type Shell/tube

Heating capacity 3200 kW

Low duty heater

1 sets

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Doc.no.: SO-1295-D / 7-Jan-11


Type Shell/tube

Heating capacity 480 kW

LNG Vapourizer

1 sets

Type Shell/tube

LNG Vaporization 3200 kW

Forcing Vaporizer

1 sets

Type Shell/tube

LNG Vaporization 1400 kW

Ballast pumps

3

Type Vert. Centrifugal

Capacity 3100 m3/h – 30 mTH

Drive Electric

Ballast stripping eductor

1

Type Ballast stripping eductor

Capacity 300 m3/h

Drive Water spray pump

Inert gas generator

1

Type I.G. generating

Capacity 14500 m3/h 25 kPag

N2 generator system

2

Type Membrane separation low pressure

Capacity 125 Nm3/h

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3.3 Properties of LNG

3.3.1 Physical Properties, Composition and Characteristics of LNG

Natural gas is a mixture of hydrocarbons which, when liquefied, form a clear colourless

and odourless liquid; LNG is usually transported and stored at a temperature very close to

its boiling point at atmospheric pressure (approximately -160 °C).

The actual LNG composition of each loading terminal such as Qatar and Oman will vary

depending on its source and on the liquefaction process, but the main constituent will

always be methane; other constituents will be small percentages of heavier hydrocarbons,

e.g. ethane, propane, butane, pentane, and possibly a small percentage of nitrogen.

The physical properties of the major constituent gases are given below:

Methane Ethane Propane Butane Pentane Nitrogen

CH4 C2H6 C3H8 C4H10 C5H12 N2

Molecular Weight 16,042 30,068 44,094 58,120 72,150 28,016

Boiling point at 1 bar

abs.

°C -161,5 -88,6 -42,5 -5 36,1 -196

Liquid Density at

boiling point

Kg/m3

426,0 544,1 580,7 601,8 610,2 808,6

Vapour SG at 15°C

and 1 bar absolute

0,554 1,046 1,540 2,07 2,49 0,97

Gas volume/liquid

volume ratio at boiling

point and 1 bar abs.

619 619 413 311 311 205

Flammable limits in

air by volume

% 5,3 - 14 3 - 12,5 2,1 - 9,5 2 - 9,5 3 – 12,4 N/A

Auto-ignition temp °C 595 510 510/583 510/583

Gross Heating value at

15°C -normal

-iso

kJ/kg

55550

51916

50367

49530

49404

49069

48944

Vaporization heat at

boiling point

kJ/kg 510,4 489,9 426,2 385,2 357,5 199,3

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..and a typical composition of LNG is given here:

Ras Laffan Das Island Standard

Methane CH4 90,28% 84,5% 89,63%

Ethane C2H6 6,33% 12,9% 6,32%

Propane n-C3H8 2,49% 1,5% 2,16%

Butane n-C4H10 0,49% 0,5% 1,2%

Iso-Butane i-C4H10 0,00% 0,00% 0,00%

Pentane n-C5H12 0,02% 0,00% 0,00%

Iso-Pentane i-C5H12 0,00% 0,00% 0,00%

Nitrogen N2 0,41% 0,6% 0,69%

Average Mol. Weight 17,88 18,56 18,12

Boiling point at atmospheric pressure -160,8 -161,0 -160,9

Density kg/m3

461,8 456,8 459,4

Higher specific energy kJ/kg 54,414 54,031 54,090

For most engineering calculations (e.g. piping pressure losses) it can be assumed that the

physical properties of pure methane represent those of LNG. However, for custody transfer

purposes when accurate calculation of the heating value and density is required, the

specific properties based on actual component analysis must be used.

During a normal sea voyage, heat is transferred to the LNG cargo through the cargo tank

insulation, causing vaporization of part of the cargo, i.e. boil-off.

The composition of the LNG is changed by this boil-off because the lighter components,

having lower boiling points at atmospheric pressure, vaporizer first.

Therefore the discharged LNG has a lower percentage content of nitrogen and methane

than the LNG as loaded, and a slightly higher percentage of ethane, propane and butane,

due to methane and nitrogen boiling off in preference to the heavier gases.

The flammability range of methane in air (21% oxygen) is approximately 5.3 to 14% (by

volume). To reduce this range, the air is diluted with nitrogen until the oxygen content is

reduced to 2% prior to loading after dry dock. In theory, an explosion cannot occur if the 02

content of the mixture is below 13% regardless of the percentage of methane, but for

practical safety reasons’, purging is continued until the 02 content is below 2%. This safety

aspect is explained in detail later in this section.

The boil-off vapour from LNG is lighter than air at vapour temperatures above -110°C or

higher depending on LNG composition, therefore when vapour is vented to atmosphere;

the vapour will tend to rise above the vent outlet and will be rapidly dispersed. When cold

vapour is mixed with ambient air the vapour-air mixture will appear as a readily visible

white cloud due to the condensation of the moisture in the air. It is normally safe to assume

that the flammable range of vapour-air mixture does not extend significantly beyond the

perimeter of the white cloud.

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The auto ignition temperature of methane, i.e. the lowest temperature to which the gas

needs to be heated to cause self-sustained combustion without ignition by a spark or flame,

is 595°C.

3.3.2 Variation of Boiling Point of Methane with Pressure

The boiling point of methane increases with pressure and this variation is shown in the

diagram for pure methane over the normal range of pressures on board the vessel. The

presence of the heavier components in LNG increases the boiling point of the cargo for a

given pressure.

The relationship between boiling point and pressure of LNG will approximately follow a

line parallel to that shown for 100% methane.

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Boiling point of methane with pressure.

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3.3.3 Flammability of Gases

Flammability of Methane, Oxygen and Nitrogen Mixtures

The ship must be operated in such a way that a flammable mixture of methane and air is

avoided at all times. The relationship between gas/air composition and flammability for all

possible mixtures of methane, air and nitrogen is shown on the diagram above.

The vertical axis A-B represents oxygen-nitrogen mixtures with no methane present,

ranging from 0% oxygen (100% nitrogen) at point A, to 21% oxygen (79% nitrogen) at

point B. The latter point represents the composition of atmospheric air.

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The horizontal axis A-C represents methane-nitrogen mixtures with no oxygen present,

ranging from 0% methane (100% nitrogen) at point A, lo 100% methane (0% nitrogen) at

point C.

Any single point on the diagram within the triangle ABC represents a mixture of all three

components, methane, oxygen and nitrogen, each present in specific proportion of the total

volume. The proportions of the three components represented by a single point can be read

off the diagram.

For example, at point D:

Methane: 6.0% (read on axis A-C)

Oxygen: 12.2% (read on axis A-B)

Nitrogen: 81.3% (remainder)

The diagram consists of three major sectors:

1. The Flammable Zone Area EDF. Any mixture whose composition is represented by a

point which lies within this area is flammable.

2. Area HDFC. Any mixture whose composition is represented by a point which lies

within this area is capable of forming a flammable mixture when mixed with air, but

contains too much methane to ignite.

3. Area ABEDH. Any mixture whose composition is represented by a point which lies

within this area is not capable of forming a flammable mixture when mixed with air.

3.3.3.1 Using the Diagram

Assume that point Y on the oxygen-nitrogen axis is joined by a straight line to point Z on

the methane-nitrogen axis. If an oxygen-nitrogen mixture of composition Y is mixed with a

methane-nitrogen mixture of composition Z, the composition of the resulting mixture will,

at all times, be represented by point X, which will move from Y to Z as increasing quantities

of mixture Z are added.

Note!

In this example point X, representing changing composition passes through the flammable

zone EDF, that is, when the methane content of the mixture is between 5.5% at point M,

and 9.0% at point N.

Applying this to the process of inerting a cargo tank prior to cool down, assume that the

tank is initially full of air at point B. Nitrogen is added until the oxygen content is reduced

to 13% at point G. The addition of methane will cause the mixture composition to change

along the line GDC which, it will be noted, does not pass through the flammable zone, but

is tangential to it at point D. If the oxygen content is reduced further, before the addition of

methane, to any point between 0% and 13%, that is, between points A and G, the change in

composition with the addition of methane will not pass through the flammable zone.

Theoretically, therefore, it is only necessary to add nitrogen to air when inerting until the

oxygen content is reduced to 13%. However, the oxygen content is reduced to 2% during

inerting because, in practice, complete mixing of air and nitrogen may not occur.

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When a tank full of methane gas is to be inerted with nitrogen prior to aeration, a similar

procedure is followed. Assume that nitrogen is added to the tank containing methane at

point C until the methane content is reduced to about 14% at point H. As air is added, the

mixture composition will change along line HDB, which, as before, is tangential at D to the

flammable zone, but does not pass through it. For the same reasons as when inerting from a

tank containing air, when inerting a tank full of methane it is necessary to go well below

the theoretical figure to a methane content of 5% because complete mixing of methane and

nitrogen may not occur in practice.

The procedures for avoiding flammable mixtures in cargo tanks and piping are summarised

as follows:

1. Tanks and piping containing air are to be inerted with nitrogen before admitting

methane until all sampling points indicate 5% or less oxygen content;

2. Tanks and piping containing methane are to be inerted with nitrogen before admitting

air until all sampling points indicate 5% methane.

It should be noted that some portable instruments for measuring methane content are based

on oxidising the sample over a heated platinum wire and measuring the increased

temperature from this combustion. This type of analyzer will not work with methane-

nitrogen mixtures that do not contain oxygen. For this reason, special portable instruments

of the infrared type have been developed and supplied to the ship for this purpose.

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3.3.4 Supplementary Characteristics

3.3.4.1 When Spilled on Water

1. Boiling of LNG is rapid, due to the large temperature difference between the product

and water.

2. LNG continuously spreads over an indefinitely large area; it results in a

magnification of its rate of evaporation until vaporization is complete.

3. No coherent ice layer forms on the water.

4. Under particular circumstances, with a methane concentration below 40%. flameless

explosions are possible when the LNG strikes the water. It results from an interfacial

phenomenon in which LNG becomes locally superheated at a maximum limit until a

rapid boiling occurs. However, commercial LNG is far richer in methane than 40%

and would require lengthy storage before ageing to that concentration.

5. The flammable cloud of LNG and air may extend for large distances downward (only

methane when warmer than -100°C is lighter than air) because of the absence of

topographic features which normally promote turbulent mixing.

3.3.4.2 Vapour Clouds

1. If there is no immediate ignition of an LNG spill, a vapour cloud may form. The

vapour cloud is long, thin; cigar shaped and, under certain meteorological conditions,

may travel a considerable distance before its concentration falls below the lower

flammable limit. This concentration is important, for the cloud could ignite and burn,

with the flame travelling back towards the originating pool. The cold vapour is

denser than air and thus, at least initially, hugs the surface. Weather conditions

largely determine the cloud dilution rate, with a thermal inversion greatly

lengthening the distance travelled before the cloud becomes non-flammable.

2. The major danger from an LNG vapour cloud occurs when it is ignited. The heat

from such a fire is a major problem. A deflagrating (simple burning) is probably fatal

to those within the cloud and outside buildings but is not a major threat to those

beyond the cloud, though there will be burns from thermal radiations.

3. When loaded in the cargo tanks, the pressure of the vapour phase is maintained as

substantially constant, slightly above atmospheric pressure.

4. The external heat passing through the tank insulation generates convection currents

within the bulk cargo; heated LNG rises to the surface and boils.

5. The heat necessary for the vaporization comes from the LNG and, as long as the

vapour is continuously removed by maintaining the pressure as substantially

constant, the LNG remains at its boiling temperature.

6. If the vapour pressure is reduced by removing more vapour than generated, the LNG

temperature will decrease. In order to make up the equilibrium pressure

corresponding to its temperature, the vaporization of LNG is accelerated, resulting in

an increased heat transfer from LNG to vapour.

3.3.4.3 Reactivity

Methane is an asphyxiant in high concentrations because it dilutes the amount of oxygen in

the air below that necessary to maintain life. Due to its inactivity, methane is not a

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significant air pollutant and, due to its insolubility, inactivity, and volatility, it is not

considered a water pollutant.

3.3.4.4 Cryogenic Temperatures

Contact with LNG or with materials chilled to its temperature of about -160°C will damage

living tissue. Most metals lose their ductility at these temperatures; LNG may cause the

brittle fracture of many materials. In case of LNG spillage on the ship's deck, the high

thermal stresses generated from the restricted possibilities of contraction of the plating will

result in the fracture of the steel.

3.3.4.5 Behaviour of LNG in the Cargo Tanks

When loaded in the cargo tanks, the pressure of the vapour phase is maintained

substantially constant, slightly above atmospheric pressure.

The external heat passing through the tank insulation generates convection currents within

the bulk cargo, causing heated LNG to rise to the surface and is then boiled-off.

The heat necessary for vaporization comes from the LNG, and as long as the vapour is

continuously removed by maintaining the pressure as substantially constant, the LNG

remains at its boiling temperature.

If the vapour pressure is reduced by removing more vapour than is generated, the LNG

temperature will decrease. In order to make up the equilibrium pressure corresponding to

its temperature, the vaporization of LNG is accelerated, resulting in an increased heat

transfer from LNG to vapour.

If the vapour pressure is increased by removing less vapour than is generated, the LNG

temperature will increase. In order to reduce the pressure to a level corresponding to the

equilibrium with its temperature, the vaporization of LNG is slowed down and the heat

transfer from LNG to vapour is reduced.

LNG is a mixture of several components with different physical properties, particularly the

vaporization rates; the more volatile fraction of the cargo vapourizers at a greater rate than

the less volatile fraction. The vapour generated by the boiling of the cargo contains a

higher concentration of the more volatile fraction than the LNG.

The properties of the LNG, i.e. the boiling point, density and heating value, have a

tendency to increase during the voyage.

3.3.4.6 Avoidance of Cold Shock to Metal

Structural steels suffer brittle fracture at low temperatures. Such failures can be

catastrophic because, in brittle steel, little energy is required to propagate a fracture once it

has been initiated. Conversely, in a tough material, the energy necessary to propagate a

crack will be insufficient to sustain it when it runs into sufficiently tough material.

Plain carbon structural steels have a brittle to ductile behaviour transition which occurs

generally in the range -50°C to +30°C. This, unfortunately, precludes their use as LNG

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materials (carriage temperature -162°C). The effect is usually monitored by measuring the

energy absorbed in breaking a notched bar and a transition curve.

For this reason, materials which do not show such sharp transition from ductile to brittle

fracture as the temperature is lowered, have found obvious application for use in cryogenic

situations in general and particularly in liquid methane carriers, for example, invar (36%

nickel-iron alloy), austenitic stainless steel, 9% nickel steel and some aluminium alloys

such as 5083 alloy. All of these materials behave in a ductile manner at -162°C, so that the

chance of an unstable brittle fracture propagating, even if the materials were overloaded, is

negligible.

In order to avoid brittle fracture occurring, measures must be taken to ensure that LNG and

liquid nitrogen do not come into contact with the steel structure of the vessel. In addition,

various equipment is provided to deal with any leakages which may occur.

The manifold areas are equipped with a stainless steel drip tray, which collects any spillage

and drains it overboard. The ship, in way of the manifolds, is provided with a water curtain

which is supplied by the deck fire main. The fire main must always be pressurized and the

manifold water curtain in operation when undertaking any cargo operation. Additionally,

fire hoses must be laid out to each liquid dome to deal with any small leakages which may

develop at valves and flanges. Permanent drip trays are fitted underneath the items most

likely to cause problems and portable drip trays are provided for any other needs.

During any type of cargo transfer, and particularly whilst loading and discharging, constant

patrolling must be conducted on deck to ensure that no leakages have developed.

In the event of a spillage or leakage, water spray should be directed at the spillage to

disperse and evaporate the liquid and to protect the steelwork. The leak must be stopped,

suspending cargo operations if necessary.

In the event of a major leakage or spillage, the cargo operations must be stopped

immediately, the general alarm sounded and the emergency deck water spray system put

into operation.

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3.4 Description of the Ship’s Equipment and

Arrangements

This section contains all particulars of the ship’s equipment and arrangements necessary to

enable the crew to follow the operational procedures set out in sections 3 and 4. This

description is based on real vessels data, so there are some points in the descriptions which

not are implemented in the simulator, but we have kept it for guidance only.

3.4.1 Design Concept of the Cargo System

3.4.1.1 General Description

The Cargo Containment System consists of four double insulated cargo tanks encased

within the inner hull and situated in-line from forward to aft.

The spaces between the inner hull and outer hull are used for ballast and will also protect

the tanks in the event of an emergency situation, such as collision or grounding.

The cargo tanks arc separated from other compartments, and from each other, by five

transverse cofferdams which are all dry compartments.

The ballast spaces around the cargo tanks are divided into two double bottom wing tanks,

port and starboard for each cargo tank. The double bottom tanks extend to the side of the

cargo tanks as far up as the trunk ways.

The LNG to be transported is stored in the four cargo tanks numbered 1 to 4, from fore to

aft. All cargo tanks have an octagonal transverse section matching with the supporting

inner hull.

Between the two transverse bulkheads, each tank is composed of a prism placed in a

direction parallel to the keel plate.

The boundaries of the tanks are as follows:

1. One flat bottom, parallel to the keel plate raised along the ship's plating by two

inclined plates, one on each side.

2. Two vertical wails each extended at their upper parts by an inclined plate, in order to

limit the liquid free surface effect when the tanks are full.

3. One flat top parallel to the trunk bottom.

Cargo tank No. l is slightly different in shape due to its position in the ship. It has a

polygonal section and the lengthwise wails are almost parallel to the ship's plating.

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3.4.2 Cargo Containment System Principle

The cargo tanks are of double membrane, Gas Transport No.96-2 Evolution System design.

The inner hull, i.e. the outer shell of each of the cargo tanks, is lined internally with the

Gas Transport integrated tank containment and insulation system.

This consists of a thin, flexible membrane called the primary membrane, which is in

contact with the cargo, a layer of plywood boxes filled with Perlite called the Primary

insulation, a second flexible membrane similar to the first one called the secondary

membrane and a second layer of boxes also filled with Perlite in contact with the inner hull

called the Secondary insulation. The double membrane system meets the requirement of

the relevant regulations on the Cargo Containment System to provide two different

“barriers” to prevent cargo leakage.

The tank lining thus consists of two identical layers of membranes and insulation so that in

the event of a leak in the primary barrier, the cargo will be contained indefinitely by the

secondary barrier. This system ensures that the whole of the cargo hydrostatic loads are

transmitted through the membranes and insulation to the inner hull plating of the ship.

The function of the membranes is to prevent leakage, while the insulation supports and

transmits the loads and, in addition, minimizing heat exchange between the cargo and the

inner hull. The secondary membrane, sandwiched between the two layers of insulation, not

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only provides a safety barrier between the two layers of insulation, but also reduces the

convection currents within the insulation.

The primary and secondary insulation spaces are under a pressure controlled nitrogen

atmosphere. The primary space's pressure must never exceed the cargo tank pressure in

order to prevent the primary membrane from collapsing inwards. In normal operation, the

pressure in the primary and secondary insulation spaces shall be maintained between 2

mbar and 0.4 mbar.

3.4.2.1 Construction of the Insulation and Barriers

The primary and secondary barriers are identical and are fabricated from cryogenic invar (a

36% nickel steel, with a very low coefficient of thermal expansion, 0.7 mm thick).

The composition of invar is:

Ni : 35 - 36.5%

C : < 0.04%

Si : < 0.25%

Mn : < 0.2 to 0.4%

S : < 0.0015%

P : < 0.008%

Fe : Remainder

Thermal expansion coefficient = (1.5±0.5) 10-6

mm/°C

between 0°C and -180 °C

(about ten times less than for stainless steel AISI 304 type)

Charpy Test at -196 °C, > 120 J/cm2

The coefficient of thermal expansion is low enough to enable flat, rather than corrugated

sheets, to be used. The entire surface area of the membrane is thus in contact with the

supporting insulation, so that the load which the system is able to carry is limited only by

the load bearing capacity of the insulation.

The primary and secondary insulation spaces are made up of boxes fabricated from

plywood and filled with expanded Perlite. This insulation system allows free circulation of

nitrogen and therefore permits gas freeing or inerting to be carried out in the barrier spaces

without difficulty.

Perlite is obtained from a vitreous rock of volcanic origin which, when heated to a high

temperature (above 800°C), is transformed into very small balls. These balls have

diameters that measure between a few hundredths to a few tenths of a millimetre. The

cellular structure so obtained from the process gives the expanded Perlite its lightness and

thus its excellent insulation properties. The water repellence of the Perlite is reduced by a

silicon treatment.

The insulation is distributed over the hull in two specific areas:

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1. Reinforced area located in the upper part of the tank and covering approximately

30% of the total tank height (including the tank ceilings). This area is fitted with

reinforced type boxes.

2. Standard area (or non-reinforced area) covering approximately 70% of the tank

height (including the tank bottom). This area is fitted with normal boxes (Refer to

Illustration 6.3.la).

The secondary and primary boxes in the reinforced area are specially built with thicker

internal stiffeners to resist the impacts which can be created by the liquid sloshing inside

the tanks. The primary reinforced boxes have two 12 mm thick plywood covers stapled on

it.

The secondary insulation is 300 mm thick, whereas the primary insulation is 230 mm is

thick. (The designed boil-off rate i.e. 0.15% of the total cargo tanks volume per day

governs the thickness.)

3.4.3 Membrane Cargo Containment

The plywood boxes forming the secondary insulation are laid on the ship's inner hull

through the transition of a hard epoxy bearing product deposited on the box in the shape of

ropes by means of an automatic depositing machine. These ropes are of adjustable

thickness and compensate for the flatness defects of the inner hull. The boxes are held in

position by stainless steel coupler rods anchored to the inner hull through their welded

sockets. To absorb the ship's hull deformation, each coupler is fitted with an elastic

coupling made up of several spring washers tightened down on the setting plates for

secondary boxes by securing nuts.

Construction of Containment system – Securing of insulation boxes.

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The number of spring washers used depends on the location of the box. Boxes on the

ballast boundaries have a higher number of spring washers (5) because the hull

deformation has the largest effect on this area.

A continuous invar tongue is held in slots running along the whole length of each

secondary box cover. The secondary membrane strakes are resistance seam welded with

the continuous tongues in between.

The primary boxes are secured in position by collar studs. The collar studs are screwed into

setting (clamp) plates for collar studs linked to the setting plate for secondary boxes by two

securing screws. A plywood bridge is installed between the two setting plates to limit any

thermal conduction through the box fixations.

To allow some flexibility, each collar stud is fitted with elastic coupling, similar to those

on the secondary boxes.

Each collar stud is fitted with a single spring washer and tightened down on the setting

plate for primary boxes by securing nuts.

The primary insulation boxes have lipped invar tongues stapled along slots running

lengthwise. Continuous invar tongues are positioned in the lip of the fixed tongues on the

boxes. The primary membrane strakes are resistance seam welded with these tongues in

between.

Each primary and secondary membrane strake terminates on an invar angle structure, 1.5

mm thick, fitted around the perimeter of each transverse bulkhead and welded to it. Due to

their superposition, the secondary and primary membranes cross each other in both ways,

forming a square tube. This is prefabricated to allow an easier creation process and

attached to the double hull by 4 anchoring bars.

With this system, the membranes are directly connected to the inner hull so that any

membrane tension is directly and uniformly taken by the ship's structure.

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Construction of containment system – Flat area

Construction of containment system – Corner

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In the secondary and primary insulation spaces respectively, the gaps between the

secondary boxes and the primary boxes are insulated with a combination of rigid insulating

materials and glass wool.

3.4.3.1 Cargo Tank Outfitting

A vapour dome is located near the geometrical centre of each cargo tank ceiling.

Each vapour dome is provided with:

1. A vapour supply/return line to supply vapour to the tank when discharging, vent

vapour from the tank whilst loading and also vent the boil-off when the tank contains

cargo.

2. Spray line arrangement for cool down purposes.

3. Two pressure/vacuum relief valves set at 250 mbar and -10 mbar vacuum, venting to

the nearest vent mast riser.

4. Pick-up for pressure sensors

5. Liquid line safety valves exhaust.

In addition, each cargo tank has a liquid dome located near the ship's centre line at the aft

part of the tank. The liquid dome supports a tripod mast made of stainless steel (304 L),

suspended from the liquid dome and held in position at the bottom of the tank by a sliding

bearing to allow for thermal expansion or contraction depending on the tank environment.

The tripod mast consists of the main discharging pipes and emergency pump well, in the

form of a three-legged trellis structure and is used to support the tank access ladder and

other piping and instrumentation equipment.

The instrumentation includes temperature and level sensors, independent high level alarm

sensors and cargo pump electric cables. The two main cargo pumps are mounted on the

base plate of the tripod mast, while the stripping/spray pump is mounted on the pump

tower support. An emergency pump column, float gauge column and the filling line are

also located in the liquid dome.

The four cargo tanks are connected with each other by the liquid, vapour and

stripping/spray headers which are located on the trunk deck. The nitrogen mains supplying

the primary and secondary insulation spaces, and other services directly associated with the

cargo system, arc also located on the trunk deck together with the fire main and deck spray

main.

3.4.4 Deterioration or Failure

The insulation system is designed to maintain the boil-off losses from the cargo at an

acceptable level, and to protect the inner hull steel from the effect of excessively low

temperature. If the insulation efficiency should deteriorate for any reason, the effect may

be a lowering of the inner hull steel temperature, i.e. a cold spot and an increase in boil-off

from the affected tank. Increased boil-off gas may be vented to the atmosphere via No.1

vent mast. The inner hull steel temperature must, however, be maintained within

acceptable limits to prevent possible brittle fracture.

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Thermocouples are distributed over the surface of the inner hull, but unless a cold spot

occurs immediately adjacent to a sensor, these can only serve as a general indication of

steel temperature. To date, the only reliable way of detecting cold spots is by frequent

visual inspections of the ballast spaces on the loaded voyage.

The grade of steel required for the inner hull of the vessel is governed by the minimum

temperature this steel will reach at minimum ambient temperature, assuming that the

primary barrier has failed, so that the LNG is in contact with the secondary membrane.

With sea and air temperatures of 0°C and failure of the primary barrier, the minimum

temperature of the inner hull steel will be about -8°C. For these conditions, Classification

Societies require a steel grade distribution as shown in the next illustration, where the tank

top and top longitudinal chamfer are in grade 'E' steel, and the remaining longitudinal

steelwork grade 'DH', both grades having a minimum operating temperature of -10°C. The

transverse watertight bulkheads between cargo tanks are of grade 'A' with glycol water

heating system.

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In addition to failure of the membrane, local cold spots can occur due to failure of the

insulation.

While the inner hull steel quality has been chosen to withstand the minimum temperature

likely to occur in service, prolonged operation at steel temperatures below 0°C will cause

ice build-up on the plating, which in turn will cause a further lowering of steel temperature

due to the insulating effect of the ice.

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To avoid this, glycol heating coils are fitted in the cofferdam spaces, of sufficient capacity

to maintain the inner hull steel temperature at 0°C under the worst conditions.

If a cold spot is detected either by the inner hull temperature measurement system, or by

visual inspection, the extent and location of the ice formation should be recorded. Small

local cold spots are not critical and, provided a close watch and record are kept as a check

against further deterioration and spreading of the ice formation, no further action is

required.

If the cold spot is extensive, or tending to spread rapidly, salt water spraying should be

carried out. In the unlikely event that this remedy is insufficient and it is considered unsafe

to delay discharge of cargo until arrival at the discharge port, the final recourse will be to

jettison the cargo via a spool piece fitted at the cargo liquid manifold, using a single main

cargo pump.

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3.4.5 Description of Cargo Pumps

3.4.5.1 General

The ship is fitted with submerged, electric, single-stage (the stripping/spray pumps are

two-stage), centrifugal cargo pumps manufactured by Ebara Cryodynamics. They are

installed at the bottom of each tank.

Two sizes of pump, main cargo and stripping/spray pumps are installed as fixed units, i.e.

two main cargo pumps and one stripping/spray pump per tank.

In addition, provision is made at each tank to introduce an emergency cargo pump in case

of total cargo pump failure. Only one emergency pump is available.

3.4.5.2 Description

Particulars

Liquid pumped LNG (S.G.=0.5)

Capacity (rated flow) 1700 m³/h

Dis. head (rated) 155.0 m

Power required (rated) 448,4 kW (Motor rated at 522,2 kW)

Efficiency 80,8%

Rotational speed 1780 rpm

Minimum starting level 0,89 m

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Doc.no.: SO-1295-D / 7-Jan-11


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Doc.no.: SO-1295-D / 7-Jan-11


Main pump

The cargo pumps are started and stopped from the Cargo Control Room (CCR). They will

be automatically stopped in the event of various shut down trips being activated both in

relation to the cargo system and the pumps themselves.

Each cargo pump electric motor is protected from:

Overload (over current)

Low-current (no load operation)

Imbalance between phases (single-phasing)

Too long starting

The main cargo pumps are direct on-line started. Swing check valves are installed inside

the tanks just down steam of the cargo pump discharge flange.

These valves assist in the reduction of any excessive liquid hammer that can occur if the

pumps are not started in accordance with the steps outlined in this section.

The power supply to the cargo pump motors is made available via cargo switch boards

which are arranged in two independent sections that are normally operated as coupled, via

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bus-tie connection, or independently. No.1 cargo switchboard supplies the No.1 pumps in

all four tanks, while No.2 cargo switchboard supplies the No.2 cargo pumps.

Each of the cargo switchboards can be supplied by either, or both, of the main

switchboards.

Due to high electrical load imposed on the cargo switchboards by the running of main

cargo pumps, there is a limitation on the number of pumps that can be run depending on

the electrical power management system (start block).

The pumps should be started individually and sequentially, as required, with the pump

discharge valve open (approximately min. 5% to max. 25%).

If the pump discharge valve position docs not open to min. 5%, pump will not be started

due to starting interlock function.

3.4.5.3 Starting Procedure for the Main Cargo Pumps

a) Check to confirm that no pumps are in starting phase.

b) Open the discharge valve to 25% (maximum).

c) Start the associated main cargo pump.

Once the pump has started (the pump symbol changes from black “stop” to “run” blue),

open the discharge valve gradually from the operator station, to give the required flow-rate.

The discharge pressure and pump motor amps are monitored and adjusted to ensure the

most efficient operation as indicated on the pump performance graph, with due regard

being taken of the head of liquid on the pump discharge flange.

The manifold On-Off valves are controlled from the mimic screen, the states of which are

indicated from limit switches.

Note!

The starting duration is 7 seconds for each pump.

Each main cargo pump is rated to discharge 1,700 m3/h at 155 m head of LNG. For

optimum discharge results, bulk discharge will be carried out with 8 pumps running in

parallel.

The pump discharge valves will be throttled to ensure optimum performance as indicated

by the pump performance graph.

During the course of discharge, changes in flow rate and tank levels will alter these

readings and the discharge valve will have to be readjusted accordingly.

Under normal conditions it should be possible to maintain the full discharge rate until the

tank level approaches approximately 2.3 m, at which time the pump will start to cavitate

and lose suction as indicated by fluctuations in the discharge pressure and ammeter

readings.

The discharge valves should be throttled to stabilise conditions and one pump stopped if

necessary. The remaining pump should be progressively throttled in to maintain suction

and to prevent the operation of the low discharge pressure trip, until a level of

approximately 0.37 m is reached.

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By trimming the vessel 1 meter or more by the stem, it should be possible to reduce the

amount of liquid remaining in the tanks before the pumps are stopped. Adjust the trim

carefully at the end of discharging cargo to give an even keel for gauging.

The cargo pumps may be run in closed circuit on their own tanks by opening the loading

valve. This may be required if the discharge is temporarily halted when the tanks are at low

level, thereby avoiding the problems of restarting with low level and low discharge

pressure.

The pump shall be tested before arrival discharge port on calm sea condition, and during

loading when the tank level is about 4-5 m subject to terminal's acceptance.

The cargo pumps will be automatically stopped should any of the following occur:

1) Cargo tank pressure below or equal to, primary insulation space pressure plus 5 mbar

(ESDS: Cargo Tank Protection).

2) Vapour header pressure below or equal to atmospheric pressure plus 3 mbar.

3) Extreme high level in cargo tank (99% volume).

4) Activation of emergency shut down trip

(10 push buttons and 12 fusible elements) (ESDS: Stage 1)

5) Activation of ship/shore pneumatic, fibre-optic or electrical shutdown (ESDS: Stage I)

6) Motor single-phasing

7) Low motor current

8) High motor current (electrical overload)

9) Low discharge pressure with time delay at starting

10) Cargo Control Room stop

1 1) Activation of ESDS stage 2

12) Cargo tank level low

ESDS signifies that all cargo plant is shut down in addition to the pump(s) on the tank(s) in

question.

Note An insulation test of all pumps is to be carried out before arrival loading and discharging

port in order to establish that all pumps are operational and to allow time for the

installation of the emergency cargo pump should it be necessary.

Note Pump should not be started or operated against closed discharge valve due to potential

damage which may result due to insufficient cooling and lubrication for the motor and

bearing and excessive vibration levels associated with zero flow conditions.

Restart of pumps in normal operation is restricted depending on the liquid level above the

submerged electric motor.

Pumps may not be restarted with tank liquid level below at 0.89 m.

1. Normal start-up

- 1st restart : minimum 5minutes after shut down

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- 2nd restart : 15 minutes after lst restart

- 3rd restart : 15 minutes after 2nd restart

No more than 4 restarts within one hour

2. Emergency start-up

For liquid level below motor centreline (approximately 1.5 m liquid in tank), restart

after 30 minutes and not more than 2 restarts within one hour.

Note

In case of a sustained locked rotor start, attempt to restart only after 30 minutes and with

no more than 2 restarts total.

Quantities of cargo remaining in tanks after stripping refer to chapt. 3.6.3 discharging.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.6 Stripping/Spray Pump

3.4.6.1 General

One spray pump is installed in each cargo tank (total 4 spray pumps), and one complete set

is provided as spare.

The spray pump is of the electric motor-driven, two-stages, centrifugal type. The spray

pump is a submerged type and must be operated in LNG liquid. Do not operate when dry.

Pump bearings are lubricated by LNG drawn in by the LNG pump.

3.4.6.2 Description

Particulars

Number of stages 2




Power required (rated) 6.9 kW (Motor rated at 22,4 kW)

Efficiency 54,4%



Stripping pump

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Doc.no.: SO-1295-D / 7-Jan-11


The instances when these pumps can be used are:

1. To cool down the liquid header prior to discharging.

2. To cool the cargo tank during ballast voyage prior to arrival at the loading terminal

by discharging LNG to the spray rails in the tanks.

3. To pump LNG from the tanks to the forcing vaporizer or LNG Vaporizer (emergency

case) when forced vaporization of LNG in the boilers is required.

4. To enable each cargo tank to be stripped as dry as possible for reasons such as

technical stop involving cargo tank entry.

Whenever possible the stripping/spray pump should be started early enough to avoid

possible starting problems due to very low tank levels (about 0.5 m minimum).

The stripping/spray pumps will be stopped automatically should any of the following

occur:

1. Cargo tank pressure below or equal to primary insulation space pressure plus 5 mbar

(ESDS: Cargo tank protection).

2. Vapour header pressure below or equal to atmospheric pressure plus 3 mbar (ESDS:

Stage I).

3. Extreme high level in cargo tank (99% volume)

4. Activation of Emergency Shut Down System trip

(10 push-buttons and 12 fusible elements) (ESDS: Stage 1)

5. Activation of ship/shore pneumatic, fibre-optic or electrical shutdown (ESDS: Stage

1)

6. Motor single-phasing

7. Low motor current

8. High motor current (Electrical overload)

9. Low discharge pressure with time delay at starting

10. Cargo Control Room stop

11. Activation of ESDS stage 2

12. Cargo tank level low low

Note An insulation resistance test of all pumps is to be carried out before arrival loading and

discharging port in order to establish that all pumps are operational and to allow time for

the installation of the emergency cargo pump should it be necessary.


submerged electric motor.

Pumps may not be restarted with tank liquid level below at 0.3 m.

1. Normal start-up

- 1st restart : minimum 5minutes after shut down

- 2nd restart : 15 minutes after 1st restart

- 3rd restart : 15 minutes after 2nd restart

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after 30minutes and not more than 2 restarts within one hour.

Note



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3.4.7 Emergency Cargo Pump

3.4.7.1 General

One spray pump is installed in each cargo tank (total 4 spray pumps), and one complete set

is provided as spare.

The spray pump is of the electric motor-driven, two-stages, centrifugal type. The spray

pump is a submerged type and must be operated in LNG liquid. Do not operate when dry.

Pump bearings are lubricated by LNG drawn in by the LNG pump.

3.4.7.2 Description

Particulars




Power required (rated) 171 kW (Motor rated at 223,8 kW)

Efficiency 67,8%



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Doc.no.: SO-1295-D / 7-Jan-11


Emergency discharge pump

Each cargo tank is equipped with an emergency pump well or column.

This pump well has a foot valve which is held in the closed position by highly loaded

springs.

Should a failure of either one or both main cargo pumps in one tank require the use of the

emergency pump, the emergency pump is lowered into the emergency pump well after the

well has been purged with nitrogen.

The weight of the emergency pump overcomes the compression of the springs to open the

foot valve.

A small flow of nitrogen should be maintained whilst the pump is being installed.

Note Before undertaking this operation it is important to reduce the tank pressure to near

atmosphere pressure and to keep it at this level throughout the entire operation.

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Doc.no.: SO-1295-D / 7-Jan-11


Electrical connections are made to the fixed junction box which is located adjacent to each

pump well.

A dedicated starter is available with one circuit breaker which is placed in No.1 cargo

switchboard. This starter supplies all 4 fixed junction boxes.

All safety devices are transferred to the emergency pump when the circuit breaker is

engaged, as they are the same for the main cargo pumps.

Note An insulation resistance test of all pumps is to be carried out before arrival loading and

discharging port in order to establish that all pumps are operational and to allow time for

the installation of the emergency cargo pump should it be necessary.


submerged electric motor. Pumps may not be restarted with tank liquid level below 0.86 m.

1. Normal start-up

- 1st restart : minimum 5 minutes after shut down

- 2nd restart : 15minutes after 1st restart

- 3rd restart : 15minutes after 2nd restart




after 30 minutes and not more than two (2) restarts within one hour.

Note



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Doc.no.: SO-1295-D / 7-Jan-11


3.4.8 H/D Compressor

3.4.8.1 General

Two sets of High Duty (H/D) compressors are provided in the cargo machinery room for

the following purposes:

a) During loading to return LNG vapour to shore

b) During initial coo1 down to return gas/vapour to shore

b) During warm-up to circulate heated cargo vapour through cargo tanks

3.4.8.2 Particulars

Main particulars are as follows:

Type : Horizontal, Turbo-compressor, Electric motor driven

Manufacturer : Atlas Copco Energas GmbH (GTO63 Tl Kl)

Capacity : 24000 m³/h

Suction press. : 104 kPaA

Suction temp : -140 C

Discharge press. : 200 kPa

Electric motor : 760 kW

3.4.8.3 Construction

The H/D compressors are single-stage radial types equipped with a spur gear. The impeller

is arranged in an overhung position on the pinion shaft. The spiral is screwed to the gear by

means of a cast flange. The suction nozzle is arranged axially, and the discharge nozzle

tangentially.

A shaft seal, fitted where the rotor passes through the casing, consists of 5 floating carbon

ring seals and prevents gas leakage. The installed shaft seal has two chambers. Leakage gas

is drawn from. the impeller-side chamber and returned to the suction side. The second

chamber is fed with dry nitrogen, which seals against the leakage gas from the impeller

side. Seal gas pressure is set manually at the reducing valve. Pressure can be set from 20 to

60 kPa. The recommended setting is 30 kPa. Seal gas consumption is approximately

2.5m³/h at 20 C and 0.11 Mpa.

The compressor gearbox is a 2-shaft in volute helical spur with thrust collars. The shafts

are borne in sleeve bearings. The thrust collars transfer the axial thrust of the pinion shaft

to the axial bearing of the low-speed driving shaft. The running speed of the input shaft is

3570 rpm (elec. Motor revolutions) and speed of the output shaft is 9552 rpm constant.

A bulkhead seal assures gas tightness between the cargo machinery room and motor room.

The seal, located in the motor room side of the bulkhead, consists of a system of chambers

with multiple carbon seal rings (consisting of three pieces) held by hose springs. The

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Doc.no.: SO-1295-D / 7-Jan-11


chambers are pressurised with dry air normally (10kPa) and with nitrogen as back up

(5kPa). Consumption is 0.5 m³/h (dry air) and 0.3 m³/h (nitrogen). The seal housing is on

an independent support which allows easy adjustment and attached to the bulkhead with

stainless steel bellows.

Lubricating oil is supplied to the compressor prior to starting by an electric motor driven

auxiliary L.O. pump. After the compressor has started, the auxiliary L.O. pump continues

to run for about 45 seconds and stops automatically. At shutdown, the auxiliary L.O. pump

starts automatically and continues to run for about 55 minutes. If oil pressure falls below

120 kPa, the auxiliary L.O. pump switches on automatically.

The pump and motor units are located in the motor room and serve as a stand-by unit when

the main, shaft driven L.O. pump fails.

An L.O. cooler is provided to keep the L.O. temperature at 48oC. Cooling water for the

L.O. cooler is supplied from the Auxiliary Control Cooling Fresh Water System (60oC). If

the L.O. temperature is low, L.O. in the sump tank can be heated by a steam heater which

is controlled by a temperature control valve (set value 50oC).

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.9 L/D Compressor

3.4.9.1 General

Two Low Duty (L/D) compressors are provided in the cargo machinery room for

maintaining constant cargo tank pressure and for delivering boil-off gas according to the

boiler demand.

Main particulars are as follows:

Type : Horizontal, Turbo-compressor, Electric motor driven

Manufacturer : Atlas Copco Energas GmbH (GTO32 Tl Kl)

Capacity : 8800 m³/h

Suction press. : 104 kPaA

Suction temp : -40 C

Discharge press. : 200 kPaA

Electric motor : 330 kw


The construction and materials are the same as for the high duty (H/D) compressors except

for the compressor capacity control.

The compressor capacity control is as follows:

The capacity of the L/D compressor is controlled by adjusting the inlet guide vane and

motor speed. The inlet guide vane and motor speed are controlled according to main boiler

demand within the respective split ranges that follow:

When the capacity is below 50%, the motor speed is kept at 1775 rpm and the Inlet

Guide Vane (IGV) is adjusted by a pneumatic actuator between –80oC and +20

oC

according to the main boilers demand signal from SSC on the Engine Control

Console (ECC).

When the capacity is above 50%, IGV is full open, the motor speed is adjusted by a

steeples and variable speed static inverter between 1775 rpm and 3550 rpm according

to demand signal from the SSC on the ECC.

The stable operating range of the compressor is restricted by the surge limit. Surges

which may cause damage to a compressor are prevented automatically by increasing

the flow through the compressor by means of a surge control valve on the

compressor discharge. Surge control is achieved by comparing the difference in

pressure between compressor suction and discharge with actual flow measured by

venture in the suction line. If the ratio of the above two signals falls below the set

value, the anti-surge controller will open the surge control valve and allow gas to be

recirculated to the compressor suction. The surge control is independent of the main

control system.

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3.4.9.3 Operation

Compressor starting can be carried out from the Engine Control Console (ECC) using the

start push button. The operational condition can be read on custom group display 2.

After pressing the “RUN” button, the compressor will be controlled by the Single Strategy

Controller (SSC) on the ECC to meet with the boiler demand according to the set value of

SSC.

The compressor can also be started from either a local control panel, a starter in the cargo

switch board room and push button next to motor side. Remote start (from ECC, local

panel and motor side) is possible when the local/remote change-over switch on the starter

is set on “REMOTE”. Setting the switch on “LOCAL” permits the start from the starter.

This change-over switch is normally set on “REMOTE”.

However, the compressor can be stopped from any control position. A normal/lock switch

is also provided next to motor side. This will inhibit motor start from any control position

when “LOCK” is selected.

Note: At free flow operation (motor stops), the aux. lubricating oil pump should be

running.

3.4.9.4 Start-up

Confirm that the gland sealing(not implemented in the simulator) nitrogen gas pressure is

at the present value (30 kPa) and bulkhead sealing air at correct pressure (10 kPa).

Confirm that the inlet guide vanes are at the minimum position (-80 )

Confirm that the surge control valves are open.

Confirm that the compressor L.O. sump tank level is acceptable and L.O. temperature is

above 25°C, start the auxiliary L.O. pump to circulate oil and heat the oil.

Confirm that the L.O. cooler coolant water valves are open.

Open the compressor suction valves from the Engine Control Console (ECC).

Open the compressor discharge valves manually.

When the start-up procedures are completed, the "READY' lamp for the L/D compressor

will light up on the ECC and local control panel.

Confirm that the "READY" lamp is lit.

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3.4.10 Gas Heater

3.4.10.1 General

A High Duty (H/D) gas heater and a Low Duty (L/D) gas heater are located in the cargo

machinery room. They are horizontal shell and U-tube, direct steam heating types.

The heaters are used for the following purposes;

a) H/D heater

Heating LNG vapour to warm-up the cargo tank for tank inverting, gas freeing

and aeration. Back-up of the L/D heater.

b) L/D heater

Heating boil-off gas from cargo tanks to use as gas fuel in the boiler.

3.4.10.2 Particulars

The design capacity of the H/D and L/D heaters is as follows;

H/D Heater L/D Heater

Gas inlet pressure 200 kPaA 200 kPaA

Gas inlet temperature -55oC -70

oC

Gas outlet pressure 180kpaA P=13kPa

Gas outlet temperature +75oC +45

oC

Maximum gas flow 43000Kg/h 8400Kg/h

Heating capacity 12600MJ/h 1900mJ/h

Heating steam pressure 834kPa 834kPa

Heating steam temperature 177oC 177

oC

Supply steam for each heater is fed from the low pressure steam generator (LPSG) in the

engine room. Each heater is provided with a steam condense drain pot and a steam trap.

Condense from each heater is returned to the drain inspection tank in the engine room

through the gas heater drain cooler and the gas heater drain tank.

3.4.10.3 Control System

Each heater has a local control board located near each heater. All control systems and the

local control board are pneumatic operated.

The gas outlet temperature can be set by the temperature controller fitted on the local

control board. Control valves for flow to the heater inlet and by-pass flow to the heater

outlet are adjusted according to the set temperature.

The L/D heater has two control valves (VG-941 & 943), VG-941 controls the flow to the

heater inlet and VG-943 controls the by-pass flow to the heater outlet. The H/D heater has

four control valves (2 pairs of valves). The large valve pair (VG-945 & 947) is used by the

H/D heater (warm-up mode) and the small valve pair (VG-946 & 948) is used for L/D

heater back-up (gas burning mode). The warm-up mode and the gas burning mode can be

selected using the selector switch on the local control board.

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When heating steam condense level is detected in the drain pot, all control valves are

closed to prevent icing in the heater shell. Under normal conditions, the condition indicator

on the local control board shows green. At trip condition, drain pot level is shown by

red/white strips. And the trip condition in also monitored by the Integrated Monitoring

System(IMS).

When tripped, all control valves are closed. They can be reset manually using the reset

switch fitted on the local control board.

The gas heater alarm set points are as follows;

Gas outset temperature high : 90oC

Gas outlet temperature low : 10oC

Drain pot level high : 195mm

(Temp. control valves close)

3.4.11 Operation of H/D heater

3.4.11.1 Start up

Select the operation mode, either WARM-UP or GAS BURN. Set the Auto / Manual

selector switch on the temp. controller to "M". This is done at the local control board.

Ensure that the gas detection system on the gas vent drain tank in operating.

Ensure that the auxiliary central cooling system Is operating and cooling water is being

supplied to the gas heater drain cooler.

Ensure that instrument air is being supplied to the local control board and the system works

well.

Manually open the vent valve on the heater shell.

Open the drain pot steam trap isolating valve.

Open the steam inlet valve and pass heating steam into the heater slowly and gradually.

Close the vent valve when steam begins to spurt out.

Check that the H/D heater outlet valve (VG-916) is open.

Check the H/D heater inlet valve (VG-915) is open.

At local control board, open the temperature control valve (VG-945 & 947 for warm-up,

VG-946 & 948 for L/D heater back up) and adjust the gas outlet temperature.

When the gas outlet temperature is steady, change the operation mode Auto/Manual switch

to “A”.

3.4.11.2 Stop

Change the operation mode Auto Manual switch to 'M' on the local control board.

Close the gas inlet control valve and stop the gas slowly and gradually.

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Close the steam inlet valve slowly so as to prevent icing after the temp. control valves are

closed.

Slowly open the vent valve an the heater shell.

Close the vent valve after the inside temperature of the shell and gas inlet and outlet piping

reach ambient temperature.

Notes:

Heating steam is supplied before gas flow into the heater to prevent icing.

When stopping, the gas flow is stopped before shutting off steam.

Drain in the heater shall be discharged enough after using the heater to avoid drain attack

in the drain pipe.

3.4.12 Operation of L/D heater

The operation of the L/D heater, start up and stop is the same as the H/D heater except the

selection of operation mode. The L/D heater has no operation mode selection switch, the

L/D heater is only used for GAS BURNING.

Notes for H/D heater also apply. Valve No. corresponding to the L/D heater as follows.

Steam inlet valve : V30970 - 3SV~704

Drain pot steam trap isolating valve : 3DV-702 (Not implemented in the simulator)

L/D heater gas master control valve : V30913 - VG-913

L/D heater outlet valve : V30914 - VG-914

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3.4.13 LNG Vaporizer

3.4.13.1 General

The LNG Vaporizer is of horizontal shell and U tube, direct steam heating type. It is

located in the cargo machinery room.

The LNG Vaporizer is used for the following;

Purging inert gas from the cargo tanks prior to cool down. LNG is supplied from the shore

to the vaporizer and the vaporized gas is led to the cargo tanks.

During cargo unloading, if the shore dose not supply return-vapour to the cargo tanks, the

LNG vaporizer produces vapour by bleeding LNG from the main line and supplies it to the

cargo tanks.

In the event that both cargo pumps fail in a cargo tank, emergency discharge by

pressurising the cargo tank is done using the LNG vaporizer. Liquid LNG is supplied to the

vaporizer by a spray pump and the vapour is led to the cargo tank for pressurising.

In the event that the inert gas generator is unable to produce inert gas, the LNG vaporizer

can produce nitrogen gas using liquid nitrogen from the shore.


The design capacity is as follows;

Inert gas purging Unloading without return gas

Gas evaporation 8500 kg/h 18000 kg/h

LNG inlet temperature -163oC -163

oC

LNG inlet pressure 290 kPa 200 kPa

Gas outlet temperature +20oC -60

oC

Gas outlet pressure 29 kPa 29 kPa

Steam for the LNG vaporizer is supplied from the low pressure steam generator (LPSG) in

the engine room. The vaporizer is provided with a steam condense drain pot and a steam

trap. Condense drain from the vaporizer is returned to the drain inspection tank in the

engine room through the gas heater drain cooler and the gas heater drain tank.

3.4.13.3 Control system

The LNG vaporizer has a local control board located near the vaporizer. Outlet gas

temperature is controlled by the temperature controller fitted on the local control board.

The outlet gas temperature can be set by the temperature controller. A pneumatic operated

control valve (VS-902), is adjusted according to the set temperature. Outlet gas

temperature is monitored by IMS.

The flow rate can be controlled using the remotely operated valve (VS-901). It is adjusted

from the Cargo Control Console (CCC).

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When heating steam condense level is detected in the drain pot, the temperature control

valve and the flow rate control valve are closed to prevent icing in the vaporizer shell.

Under normal conditions, the condition indicator on the local control board shows green.

At trip condition, the drain pot level is shown by red / white strips. The trip condition is

also monitored by the IMS.

If the flow rate control valve is fully closed due to accidental operation at the CCC, then

the temperature control valve is forced closed. This condition is interpreted by the

Integrated Monitoring System (IMS) as a trip condition. The condition indicator on the

local control board also shows red / white strips instead of green.

When tripped, both temperature and flow rate control valves are closed. They must be reset

manually using the reset switch on the local control board.

LNG vaporizer alarm set points are as follows;

Gas outlet temperature high : 80oC

Gas outlet temperature low : -70oC

Drain pot level high : 195mm

3.4.14 Operation

3.4.14.1 Start up

Select the spray nozzle according to the operation mode. These modes are inert gas

purging, unloading without return gas or emergency discharge. In unloading without return

gas mode, use a 1-1/2 inch spray nozzle. Use a 1 inch spray nozzle for the other modes. (a

1 inch spray nozzle is set in the vaporizer at delivery.)

At the local control board, set the Auto / Manual selector switch on the temp controller to

"M.

Ensure that the gas detection system on the gas vent drain tank is operating.

Ensure that the auxiliary central cooling system is operating and cooling water is being

supplied to the gas heater drain cooler.

Ensure that instrument air is being supplied to the local control board and the system works

well.

Manually open the vent valve on the vaporizer shell.

Open the drain pot steam trap Isolating valve (3DV-704)

Open the steam inlet valve (3SV-706) and pass heating steam into the vaporizer slowly and

gradually.

Close the vent valve when steam begins to spout out.

Open the flow control valve (VS-901) using the local valve handle and then open the

temperature control valve (VS-902) using the local temp. controller. Do this slowly and

gradually.

Adjust both flow and temperature control valves locally until gas outlet temperature is

steady.

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Doc.no.: SO-1295-D / 7-Jan-11


When the gas outlet temperature is steady, then change the operation mode Auto / Manual

switch on the temperature controller to "A".

Under normal operating conditions, the flowrate is adjusted by the flow control valve (VS-

501). This is done manually from the CCC in accordance with the cargo tank pressure.

3.4.14.2 Stop

Change the operation mode Auto / Manual switch on the local. temperature controller to

“M”.

Close the flow control valve using the local valve handling and the temperature control

valve using the local temperature controller. Stop the LNG slowly and gradually.

Close the steam inlet valve slowly so as to prevent icing after the flow and temp. control

valves are closed.

Slowly open the vent valve for the vaporizer shell.

Close the vent valve completely after the inside temperature of shell and LNG inlet and

outlet piping reach the ambient temperature.

Notes:

Heating steam is supplied first to prevent icing.

When stopping, the LNG liquid supply is stopped before shutting off steam.

The flow control valve is not closed fully during normal operation.

When exchanging the spray nozzle, the vaporizer is purged with nitrogen gas.


in the drain pipe.

Do not start the vaporizer to vaporize LNG unless the drain pot is at operational

temperature.

3.4.15 Forcing Vaporizer

3.4.15.1 General

The forcing vaporizer is a horizontal shel1 and U tube, direct steam heating type. It is

located in the cargo machinery room.

The forcing vaporizer is used for producing LNG vapour to be sent to the main boiler as

fuel gas. The produced LNG vapour is added to natural boil-off gas from cargo tanks.


The design capacity of the forcing vaporizer is as follows;

Gas evapouration : 6400 kg/h (min. 1000kg/h)

LNG inlet temperature : -163oC

LNG inlet pressure : 290 kPa

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Doc.no.: SO-1295-D / 7-Jan-11


Gas outlet temperature : -40oC

Gas outlet pressure : 25 kPa

Supply steam for the forcing vaporizer is fed from the engine room.

3.4.15.3 Control system

The forcing vaporizer is provided with a local control board located near the vaporizer.

Outlet gas temperature is controlled by the temperature controller fitted on the local control

board.

Outlet gas temperature can be set by the temperature controller and a pneumatic control

valve (V32904, VS-904), is adjusted according to the set temperature. Temperature of the

outlet gas is monitored by the Integrated Monitoring System (IMS).

The outlet gas flow rate is controlled by a PID controller. The control signal of the flow

rate is determined as the additional flow to the natural boil-off gas flow. The control signal

is calculated using the following formula by the SSC: Main boiler gas consumption minus

available gas flow from cargo tanks. The gas flow rate is adjusted by the pneumatic type

flow control valve (V32903, VS-903), according to the signal from the PID.

When the gas temperature in the mist separator becomes too low because of mixing with

the natural boil-off gas, a low temperature signal is sent to the IMS and both temperature

control valve and flow rate control valve are closed as trip condition so as not to send cold

gas, which might include LNG mist, to the gas compressor.

The trip condition must be reset by the reset switch fitted on the local control board after

recovery of trip cause.

Forcing vaporizer alarm/trip set points are as follows;

Gas outlet temperature high : 80oC

Gas outlet temperature low : -70oC

Mist separator temperature low : -145oC

3.4.16 Operation

3.4.16.1 Start up

Change the operation mode of the flow and temp. control valves from "A" to "M". This is

done at the manual loader and temp. controller on the local control board.

Ensure that the heating steam. supply pressure is at 0.3 MPa. Do this by adjusting the

steam inlet valve (V32980, 3SV-801).

Open the valve (V32980, 3SV-801) and pass heating steam into the vaporizer slowly and

gradually.

Open the flow control valve (V32903, VS-903) and the temp. control valve (V32904; VS-

904) using the manual loader and temp. controller. Do this slowly and gradually.

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Doc.no.: SO-1295-D / 7-Jan-11


Adjust both flow and temp. control valves locally until the gas outlet temperature is steady.

When the vaporizer gas outlet temperature is steady, then change the operation mode of the

flow and temp. control valves to "A" on the local control board.

Under normal operating conditions, the flow rate is controlled automatically according to a

control signal from the SSC.

3.4.16.2 Stop

Change the operating mode of the flow and temp. control valves from “A” to “M”. This is


Close the flow and temp. control valves (V32904, VS-904 & V32903, VS-903) manually

from the manual loader and temp. controller. Stop the LNG flow slowly and gradually.

Close the steam inlet valve slowly so as to prevent icing after the flow and temp. control

valves are closed.

Open the vent valve for the vaporizer shell slowly.

Close the vent valve completely after the Inside temperatures of the shell, LNG inlet and

outlet piping reach ambient temperature.

Note:

Heating steam is supplied first to prevent icing.

When stopping, LNG liquid supply is stopped before shutting off steam.


in the drain pipe.

Do not start vaporizer to vaporize LNG unless the drain pot is at operational temperature.

3.4.17 Nitrogen Generating System

3.4.17.1 General

The nitrogen generating system is installed on the 2nd deck in the engine room.

It is used for the following purposes:

Cargo line purging.

Cargo compressors (H/D,L/D) gland sealing & bulkhead sealing.

Cargo tank insulation space inerting.

Vent riser fire extinguishing.

Engine room gas line purging.


Nitrogen generator; 2 sets

Type : Membrane permeation

Capacity : 90 Nm3/h

Outlet press. : 490 kPa

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Nitrogen purity : 97% (by vol.N₂+Ar)

Max. outlet temp. : 50oC

Dew point at atm. press. : -65oC

Feed air compressor ; 2 sets

Type : Screw compressor electric motor driven

Capacity : 280 Nm3 /h

Discharge press. : 1450 kPa

N2 buffer tank ; 1 set

Capacity : 10 m3

Working press. : 300 500 kPa


Ambient air is compressed by the water cooled screw compressor. Some condense water

will be. separated in the cyclone separator (F-4A/B) and automatically drained out. Then

the saturated air passes through three filters (F-1A/B,2A/B,3A/B).

The treated compressed air is heated by the electric heater before entering the membranes.

The heated air then passes the membranes and is separated into two streams. One stream is

nitrogen, the other is the remaining gases.

In downstream of the membranes, the nitrogen passes through the flow indicator (F1-

1A/B), the purity control valve (HCV-1A/B) and the back pressure regulator (PCV-1A/B),

and is led to the nitrogen buffer tank. The other gases are discharged to the atmosphere.

This system is simplified in the simulator.

3.4.17.4 Operation

The nitrogen generator (MD340) is started / stopped locally.

Once the system has been started from the local control panel, the feed air compressor is

started and stopped automatically in response to the pressure in the nitrogen buffer tank

(start : 300 kPa, stop : 500 kPa).

When plant is stopped which means that the generator inlet and outlet valves are closed

and vent valves are open, the compressor will continue idling for a few more minutes and

stop.

If the plant has been stopped for several hours, the membranes are cold and will therefore

not separate properly for about 15 minutes after start-up. The nitrogen gas can be sent after

about 15 minutes. This delay is reduced in the simulator.

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Doc.no.: SO-1295-D / 7-Jan-11


Confirm that the oxygen content in the N2 buffer tank is below 3.5% before you open

supply to consuming systems, reduce O2 in the buffer tank by venting the it by opening

V34070.

3.4.17.5 Initial Start-up

Before start-up, check all drain valves(not implemented in the sim)on the filters for the

presence of water.

Open manually operated valves, V34001 & V34051

Switch ON the isolating switch on the El. Heater control panel.

Switch ON the main isolating switch on the Nitrogen system control panel.

Switch ON the oxygen analysers and calibrate in accordance with manufacturer's manual.

Select the process trains and put the selector switch in the position corresponding to the

following operational scenarios.

3.4.17.6 Single train operation

Position 1.:

(Crossover valve invar angle (V34040; XV-4 is CLOSED)

Compressor A operates with side A of the nitrogen generator or compressor B operates

with side B of the nitrogen generator.

Position 2.:

(Crossover valve (V34040; XV-4 is OPENED))

Compressor A operates with side B or compressor B with side A.

Note:

SELECTORS SWITCH

Position 1 COMPR A N2 GEN. A

COMPR B N2 GEN. B

Position 2 COMPR A N2 GEN. B

COMPR B N2 GEN. A

3.4.17.7 Double train operation

Position 1 should always be selected.

Confirm that the manual isolation valves are OPEN.

Confirm that all valves upstream of the nitrogen buffer tank are OPEN.

Put the local panel compressor selector on REMOTE.

Shut-off valve will remain in the "SHUT" position and vent valve in the "OPEN" position

until oxygen content is less than the set point of alarm OAHH-1A (Ref to alarm list).

Once the oxygen content is less than the set point of the alarm, the shut-off valve will

OPEN and start to deliver nitrogen gas to the buffer tank.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.17.8 Stop

Press the STOP button on the compressor control panel.

Open all filter drain valves.

If the system is to be out of service for a long time, switch off the isolating switches

(Nitrogen system control panel, electric heater panel, oxygen analyser).

3.4.17.9 Safety

Nitrogen is a non-toxic but asphyxiating gas. Its density is slightly lower than air.

3.4.18 Inert Gas Generator Plant

3.4.18.1 General

The inert gas generator plant sends inert gas or dry air to cargo tanks and cargo holds.

The plant consists of two air blowers, an inert gas generator, an Inert gas refrigerating unit

and an inert gas dryer unit (the two latter shown as only one unit).

The inert gas generator plant is in the IGG Room on the 3rd deck of the engine room.


The design capacity of the IGG is as follows;

Inert gas capacity : 11000 Nm3/h

Discharge pressure : 0.025 MPa

Temperature : Average 30oC (Max 65

oC)

Dewpoint after expansion : Maximum –45oC

to atmospheric pressure

Dry inert gas composition is as follows;

Oxygen O2 : Maximum 1.0 %

Carbon-dioxide CO2 : Maximum 14.0 vol %

Carbon-monoxide CO : Maximum 100 ppm

Sulphur-oxides SOx : Maximum 10 ppm

Nitrogen N2 : balance

3.4.18.3 Construction of the Inert gas generator (IGG)

The inert gas generator consists of a combustion chamber and a cooling/washing tower. In

the combustion chamber, fuel oil and air are burnt and inert gas is generated. Then the inert

gas is sent to the cooling/washing tower. At the cooling/washing tower, a sea water shower

cools the inert gas and washes out sulphur oxides which are contained in the gas.

The NO.3 ballast pump supplies sea water to the cooling/washing tower and the cooling

jacket of the combustion chamber.

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The IGG fuel Oil Pump supplies fuel oil from IGG gas oil tanks. The combustion air is

supplied by roots type air blowers. The final discharge pressure of the dryer unit is

maintained by the air blowers, and the pressure is controlled by a pressure control valve.

3.4.18.4 Inert gas refrigerating unit (Freon R-22)

This is not shown in the simulator

The inert gas refrigerating unit cools the inert gas as the first step of drying.

The inert gas refrigerating unit consists of a freon compressor with capacity control, a

freon condenser, a freon evapourator and a demister.

The freon evapourator is a shell and tube type cooler. Direct expanded freon 'R-22' cools

inert gas and condenses excess water in the inert gas.

3.4.18.5 Inertgas dryer unit

The dryer unit absorbs water in the inert gas with activated alumina.

The inert gas dryer unit has two dryer vessels. When one vessel is working, the other

vessel is regenerating.

The change-over between working/regenerating is carried out automatically every 8 hours.

In the regenerating phase, the vessel is heated by hot air for at least 4 hours, and then

cooled.

The hot air is generated by both electric and steam heaters. The temperature of hot air is

controlled about 220oC by electric heater.

3.4.18.6 Control and monitor

The final discharge pressure (0.25MPa) of the inert gas plant is controlled by the pressure

control valve.

The oxygen content can be adjusted manually by changing the fuel oil/air ratio. (This is

done automatically in the simulator).

When oxygen content rises above the high high level (2 %), the discharge valve will close

and the purge valve will open.

The inert gas is blown-off to the atmosphere.

Dew point is measured continuously by the dew point analyser. If a high high condition (-

40oC) continues for 15 minutes, the inert gas is blown-off too.

3.4.18.7 Preparation of Starting-up

Before starting the system:

Open IGG Scrubber SW overboard valve (V35014)-MD 350 and the Inert Gas Cooling

Water valve (V40142, 2WV-41)-MD 401

Start the No.3 ballast pump(MD401) after lining up for cooling of IG system scrubber.

Line up from the IG system to the tanks or holds in question.

Dryer unit and inert gas refrigerating unit which is shown as one unit will work

automatically, and need no attention here.

Set the O2 analyser to OFF.

Open the valve to above funnel.

3.4.18.8 Inert gas production

Open the fuel supply valve to the burner.

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Doc.no.: SO-1295-D / 7-Jan-11


Line up and start one or two fans.

Switch on the burner.

After the O2 has stabilised at a low level switch ON the O2 analyser and change over from

above funnel to delivery line. Adjust pressure level at the PID control.

3.4.18.9 Dry air production (on cargo tank aeration)

Use the same procedure as for inert gas production, but leave the burner and the O2

analyser OFF.

3.4.18.10 Stop

There is a certain way to shut down the IG plant in real life. On the simulator you may shut

of the different valves for supply, and then shut down the complete plant step by step

without any great concern. Remember to shut down the ballast pump no 3 and its valves as

well.

3.4.19 Cargo Control Console (CCC)

The CCC is in the Cargo Control Room.

3.4.19.1 Composition

The simulator works in a semi mode where all mimic panels are presented on the screen.

Therefore it may act as “real equipment” where the operator are walking on deck and

adjusting the different valves directly. Or it may act as a mimic panel in the CC room

where the operation of the equipment will be remotely controlled.

Most mimic pictures are of this semi type. However the Cargo Control Panels (1-5), and

H/D & Spray Control Panels are looked upon as if they where positioned in the CC room.

These panels are composed of the following equipment for remote operation;

Port and Starboard cargo pumps with discharge control and tank temperature setter control

for each tank.

Cargo tank spray pump and spray header control for each tank.

Control for high duty compressor no 1 & 2.

See also the IMS control.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.20 IMS control function

3.4.20.1 General

The IMS provides the following control functions.

For machinery:

- Low duty compressor control

- Forcing vaporizer control

For cargo:

- High duty compressor control

- Tank pressure control

- Spray pump start/stop, (Spray pump load control), (spray header press control).

- Spray line cool down

- Equator temperature control

- Cargo pumps start/stop, (Cargo pump load control).

- Discharging

The main components of the control functions are the Signal Strategy Controller (SSC) for

continuous PID control of sequence and logic control.

The Single Strategy Controller (SSC) is a stand alone programmable controller and is

located on the CCC.

The data setter allows setting of variable data for cargo pump stop/striping level.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.21 BVG management system

3.4.21.1 General

The BVG (Boil-off and Vapour Gas) management system is a total gas flow control from

cargo tanks to main boilers. The total gas flow consists of the following two kind of gas;

Natural boil-off gas (Natural BOG) from cargo tanks.

Forcing boil-off gas (Forcing BOG) generated by forcing vaporizer.

The natural BOG is sent to the main boilers by the L/D compressor through the low duty

heater and the flow rate is controlled by an L/D compressor speed & inlet guide vane

(IGV). If natural BOG does not meet boiler demand, the forcing vaporizer will generate

forcing BOG and add it to the natural BOG for full speed range of ship.

3.4.21.2 System configuration

BVG management system consists of the following control system:

Vent control

The vent valve is operated by the signal from the cargo pressure controller for tank

protection.

The vent valve is opened at 23Kpa in vapour header and closed at 21Kpa.

Tank pressure control

The control system maintains the pressure in cargo tanks at a present value.

The control system calculates the available gas flow and excess gas flow.

Forcing vaporizer control

The control system controls the flow rate of forcing vaporizer.

Gas heater control

The control system controls the outlet temperature of low duty heater at a present

value.

Low Duty (L/D) compressor control

The control system controls the inlet vane opening and revolutions of. The low duty

compressor according to boiler fuel gas demand.

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3.4.22 Low duty compressor control

3.4.22.1 General

This control system controls the inlet vane opening and the revolutions of the low duty

compressor according to boiler fuel gas demand.

3.4.22.2 Operation

Line up for use of the L/D compressor.

Start the aux. L.O. pump of the selected low duty compressor.

Confirm that L.O. temperature and pressure are OK, and that the READY lamp is lit.

Start the low duty compressor on the compressor control panel by pushing START.

After confirming steady running of the low duty compressor, change the control mode of

the PID controller to AUTO mode.

The low duty compressor can be controlled according to the boiler fuel gas demand.

Stop operation

Push the STOP button for the low duty compressor on the control panel.

The Aux. L.O. pump starts automatically and continues running 55min after the stop

signal.

The PID control mode will change to MANUAL automatically when both low duty

compressors are stopped.

3.4.23 Control logic

Boiler fuel gas demand is detected by the boiler gas flow control valve position. The valve

position signal which is selected from NO.1 and NO.2 boilers by high selecter is sent to the

PID controller as the process value (PV).

The difference between the process value and the pre-set value (SP) in the PID controller

becomes the output signal. The out-put signal is divided into two signals; the inlet vane

control signal and the revolution control signal for the low duty compressor.

Inlet vane control 0 35%

Revolution control 35 100%

When the vapour header pressure decreases to the pre-set value (3kpa), the SSC outputs a

F.O. back-up order signal to the boiler automatic combustion control system(ACC). After

confirmation of F.O. burning signal from the ACC, the output signal from the PID

controller is set to minimum, the inlet vane fully closed and revolutions set to minimum.

When both low duty compressors are stopped, the SSC control mode is set to MANUAL

automatically.

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3.4.24 Forcing vaporizer control

3.4.24.1 General

This control system controls the flow rate of the forcing vaporizer based on the difference

between actual boiler gas flow (fuel gas consumption) and available natural Boil Off Gas

(BOG) from cargo tanks.

3.4.24.2 Start operation

Change the operation mode of the flow and temp. control valves from "A" to "M". This is


Ensure that the heating steam. supply pressure is at 0.3 MPa. Do this by adjusting the

press. reducing valve (3SV-718).

Open the steam inlet valve (3SV-801) and pass heating steam into the vaporizer slowly and

gradually.

Open the flow control valve (VS-905) and the temp. control valve (VS-904) using the

manual loader and temp. controller. Do this slowly and gradually.

Adjust both flow and temp. control valves locally until the gas outlet temperature is steady.

When the vaporizer gas outlet temperature is steady, then change the operation mode of the

flow and temp. control valves to "A" on the local control board.

Ensure that the PID controller operate in order to help the set value to approach the process

value.

Confirm the forcing vaporizer outlet temperature controller is operating.

Change the control mode to “C”.

3.4.24.3 Stop operation

Change the control mode to “A”.

Change the flow control valve manual loader on the local control board to “M”.

Local operation at the local control board is carried out.

3.4.24.4 Control logic

The total fuel gas consumption for the boiler is measured by the boiler automatic

combustion control (ACC) and is compared with the available BOG flow from cargo tanks.

The difference between those values is sent to the PID controller as set point.

The measured flow signal from the forcing vaporizer is also sent to the PID controller and

the output signal from the PID controller is sent to the forcing vaporizer gas flow control

valve.

3.4.25 High duty compressor control

3.4.25.1 General

Two high duty compressor controllers (SSC) are on the Cargo Control Console (MD500).

The control system controls the inlet vane in the high duty compressor so as to keep the

vapour header pressure constant.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.25.2 Start operation

Switch to mimic MD 319 and start the aux. L.O. pump for the high duty compressor in

question by clicking with the left mouse button on the LO icon.

Open N2 Supply. Open suction inlet valve and discharge valve. Check that the vane is set

to -80º.

L.O. temperature, pressure and the related valves are confirmed ready.

Ensure that the READY lamp is lit.

Ensure that the START AVAIL lamp on is lit.

Ensure that the SSC is in MAN mode.

Start the high duty compressor by pushing the START button.

Set the vapour header pressure (which is the pressure in the Vapour. line which the

compressors are sucking from). Typical setting is 5-10 kPa.

After confirming that the high duty compressor is running steady, change the control mode

of the SSC to AUTO.

Adjust the set point of vapour header pressure according to the actual vapour header

pressure.

The second high duty compressor is started if necessary.

3.4.25.3 Stop operation

Change the control mode on the SSC to MAN.

Decrease the PID output signal to 0 gradually.

Push the STOP button. The aux. L.O. pump will start automatically and continue running

for 55 min after the stop order.

3.4.25.4 Control logic

The measured vapour header pressure signal is sent to the PID controller as a process

value. The difference between the set point and the process value in the PID controller

becomes the output signal and is sent to the inlet vane actuator.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.26 Spray Pump Start/Stop

3.4.26.1 General

The spray pump is started and stopped sequentially by controlling a discharge valve and a

return valve.

The spray pumps and the relevant valves are controlled by the spray pump load controller

(SSC) and the spray header pressure controller (SSC).

The flow chart of the control function is shown below.

3.4.26.2 Sequence control

The sequence control will carry out the following operation by choosing AUTO mode.

The spray pump discharge valve opens to the present position (7%)

The tank spray return valve opens to 100%

Spray pump starts

Timer counting (10 sec)

Initial control set point (35% motor load) of the SSC is set.

Initial control set point (Spray header press : 350 kPa) of the SSC is set,

Motor load is controlled by the adjustment of the spray pump discharge valve.

Spray header pressure is controlled by the adjustment of the tank spray return valve.

The control set point of SSC returns to the initial set point just before the finish of PLC.

The sequence control will carry out the following operation by choosing MAN mode.

The tank spray return valve opens to 100%

The spray pump discharge valve closes to 0%

The spray pump will have to be stopped manually by clicking the right mouse button on

the icon.

3.4.26.3 Caution

Spray pump cannot be started at the tank level less than 2.0 m normally.

It is necessary to block the low level alarm (CTS) when the pump is started at the tank

level less then 2.0 m.

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Doc.no.: SO-1295-D / 7-Jan-11


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Doc.no.: SO-1295-D / 7-Jan-11


3.4.27 Spray line Cooldown

3.4.27.1 General

Spray line cool down is controlled from the Cargo Control Console (CCC).

Spray line cool down is carried out before spraying, if necessary.


The sequence control will carry out the following operation:

All spray valves open.

Time counting (60 sec).

All spray valves close.

Activate chime ring for ten seconds (works only if sound system is enabled).

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.28 Cargo Pump Start/Stop

3.4.28.1 General

The cargo pump is started and stopped sequentially by controlling a discharge valve and a

filling valve.

The flow chart of the control function is shown below.

The cargo pumps and the relevant valves are controlled by the Programmable Logic

Controller (PLC) in combination with the cargo pump load controller (SSC).

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Doc.no.: SO-1295-D / 7-Jan-11


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Doc.no.: SO-1295-D / 7-Jan-11


3.4.28.2 Pump stop level

There are two modes for the stop sequence: “STOP MODE” and “STRIPPING MODE”. In

both modes stop level should be input manually.

Each pump will be in the following mode automatically by the stop level input.

Where L01 = stop level for No.1 pump

L02 = stop level for No.2 pump

Mode of pump

No.1 pump No.2 pump

L01 < L02 Stripping Stop

L02 < L01 Stop Stripping

L01 = L02 Stop Stop

Note:

Allowable input level range as follows:

0 L01 15m 0 L02 15m

The cargo pump is protected against low current which will be caused by running at low

tank level.

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Doc.no.: SO-1295-D / 7-Jan-11



The sequence controller will carry out the following after pushing the START button on

the Automatic Sequence panel. This manual shows the normal start of cargo pumps in

No.1 cargo tank.

3.4.28.4 Pump start

Confirmation of cargo pump start available

The Cargo Pump Discharge valve opens to the preset position (12%).

The Filling valve opens to 100%.

The Liquid Branch valve (out of the tank) closes to 0%.

Pump starts (No.1 or No.2)

Timer counting

Initial control set point (42.3% motor load) of the SSC is set

In compliance with the set point, the pump discharge valve opens or closes to maintain the

motor current constantly.

(Starting Discharge operation see next page)

3.4.28.5 Pump stop “STOP MODE”

When the tank level reaches the stop level (L1 or L2), the pump discharge valve closes to

the preset position.

Timer counting

Pump stops

The pump discharge valve closes to 0%.

(Required time about 20 30 sec.)

3.4.28.6 Pump stop “STRIPPING MODE”

When the tank level reaches the stop level, chime activates.

Note: In this case the operator must stop cargo pump manually.

3.4.28.7 Caution

The Cargo pumps cannot be started at a tank level less than 2.0m normally.

It is necessary to block the low level alarm (CTS) when the pump is started at a tank level

less then 2.0m. This figure is adjustable by keyboard operation on CTS.

When this sequence control is started when the cargo pump is running, the discharge valve

is returned to the preset position(initial load).

Cargo pump stop sequence control utilises the level signal (0-15 meters) from CTS main

level segment.

3.4.29 Discharging

3.4.29.1 General

The liquid branch valve and filling valve automatically open and close by the

Programmable Logic Controller (PLC).

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The sequence controller will carry out the following operation by pushing the START

button on the Automatic Sequence panel. This manual shows the discharging of No.1 tank.

Confirmation of the setting of the Filling valve ( 95 %) and the Liquid branch valve

( 3%).

Liquid branch valve opens to 100%

Timer counting (20 seconds from the open signal of this valve)

The Filling valve closes to 0%.

Note: The CTS measuring system must be on during cargo operations.

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Doc.no.: SO-1295-D / 7-Jan-11


3.4.30 Cargo Tank Temperature Control

3.4.30.1 General

During ballast voyage, the equator temperature of the cargo tank can be maintained at a

present value by automatic control of spraying.

Temperature control is done through the NO.3 spray nozzle valve (nominal capacity 2,35

t/h /tank ) of each tank.

The control temperature is measured by four thermo resistance bulbs (three wire type pt

100 at 0oC) which are provided forward, aft, port and starboard at equator level of each

tank.

“Cargo tank pressure control” stops spraying when the tank pressure reaches the preset

value.

3.4.30.2 Operation

Preparation:

Start spray pump (refer to “Spray pump”)

Cool down spray line

Set the variable value for spray header pressure controller.

Push the “START” button at the Auto Sequence panel on the Tank Temp Setter.

Set the equator temperature.

Caution: Equator temperature should reach below –124oC before starting of normal

loading.

To stop push the “STOP” switch at the Auto Sequence panel on the Tank Temp Setter.

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3.4.31 Cargo Tank Pressure Control

3.4.31.1 General

During ballast or laden voyage, pressure of the cargo tank can be maintained at a present

value by controlling amount of vapour generated by forcing vaporizer.

3.4.31.2 Description

Two sets of controllers are provided for this function. One controls tank pressure by

measuring gauge pressure at the vapour header, and the other controls by measuring

absolute pressure.

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Selection one of the two tank pressure controllers is done using the changeover switch on

the CCC.

The way to control tank pressure in relation with the gas supply and demand condition is as

follows;

Natural BOG > boiler demand Dump, Vent or Pressurising

Natural BOG + spraying > boiler demand Dump, Vent or Pressurising

Natural BOG + forcing + spraying > boiler demand Decrease the flow from vaporizer

Natural BOG + forcing + spraying < boiler demand Increase the flow from vaporizer

Natural BOG + spraying < boiler demand Forcing

Natural BOG < boiler demand Forcing and/or Spraying

Regarding the acceptable pressure range of the cargo tank, refer to "Cargo tank protection

system”.

3.4.32 Cargo Tank Protection System

3.4.32.1 General

An instrumented tank protection system is provided.

In addition to the level measurement, three level alarms for each tank (in the custody

transfer system) are provided, whereof one is adjustable

Thermo-resistance bulbs are provided to monitor the temperature of the cargo tank and

hold.

3.4.32.2 Level alarm and safety

A High level alarm is provided in each cargo tank. It is initiated by a capacitance level

sensor and is set at 97.0% volume.

A High-High level alarm is provided in each cargo tank. It is initiated by a capacitance

level sensor and is set at 99.0 % volume level. The tank filling valve for each cargo tank is

closed automatically by the High-High level signal mentioned above.

Moreover, an Emergency Shut Down system (ESD) is activated by the signal from a

capacitance spot sensor at 99.5 % volume level.

3.4.32.3 Pressure alarm and safety

A High pressure alarm for each cargo tank is provided, and is set at 22 kPa. The vapour

header pressure control valve is opened at 23 kPa. The pilot operated relief valve of each

cargo tank releases excess vapour in the cargo tank to the atmosphere at 25 kPa.

A Low pressure alarm is provided for each cargo tank and is set at 1 kpa. An automatic trip

system for the gas compressors, cargo pumps, spray pumps, IGG, ESD valves, spray inlet

valves and fuel gas master valve is activated when the pressure of any one of the cargo

tanks is equal to the atmosphere.

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A High pressure alarm for each hold is provided, and is set at 12kPa. The pilot operated

relief valves of each hold space release excess air in the atmosphere at 15kPa.

A Low pressure alarm for each hold is provided, and is set at -2kPa.

A Dry air supply request alarm for each hold is provided and set at -2kPa.

The pilot operated relief valves of each hold introduce atmospheric air to the hold space

when the pressure drops to -5kPa.

A high differential pressure alarm for each tank and hold is provided, and is set at 3kPa of

excess pressure in hold. An automatic trip system for gas compressors, cargo pumps, spray

pumps, IGG, spray inlet valves, fuel gas master valve and emergency shut down valves is

activated at 4kPa of excess pressure in the hold.

Moreover differential pressure relief valves (for each hold) release air in the hold to the

atmosphere at 5kPa of excess pressure in the hold.

3.4.32.4 Temperature alarm and safety

Ten temperature sensors in each tank are provided. Five are for service and five are for

spare. They are located at bottom, 25% level, 50% level, 75% level and 100% level in each

tank.

Four temperature sensors are provided at the equator level for each tank.

There are four temperature sensors for each hold space (side bulkhead, foundation deck,

double bottom and drip-pan), and three temperature sensors for the forward bulkheads.

A low temperature alarm indicates a cargo leakage or tank insulation failure.

3.4.33 Description of Ballast Tanks and Ballast Pumping

3.4.33.1 Segregated Ballast System

The ship is equipped with a segregated ballast system comprising a total of 15 water ballast

tanks.

All valves in the ballast system are single actuated butterfly valves.

All the valves are hydraulically remote controlled from the cargo control room.

Three electrically driven self priming ballast pumps, with a capacity of 3000 m3/h at 35

mLc (SW) each, are provided.

One ballast ejector with a capacity of 300 m3/h at 20 mLc (SW) is also provided.

The above pumps and ejector cannot be used in the cargo system and consequently they do

not require consideration with Annex II in MARPOL 73/78.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5 Mimic Diagrams

The Picture Directory will give the operator an overview of all process pictures. From this

directory any picture can be selected by clicking on the name field of the picture.

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3.5.1 Cargo Tank Overview

The Cargo Tank Overview will give the operator a total view of the cargo tanks with

information about the cargo and tank level, shown as a bar graph, as well as vital data of

the ship’s condition like trim, list, deadweight, stability and draught. The small picture of

the ship at the bottom of the page makes it possible to quickly change the picture to either

one of the cargo tanks, or holds by just clicking at the corresponding area of the small ship.

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3.5.2 Ballast Tank Overview

The Ballast Tank Overview picture will give an overview of all the ballast tanks with

information about the fillage of the tanks shown as a bar graph. Ship conditions will be

dynamically updated based on tank ullage.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.3 Bunker/Consumables

The Bunker/Consumables Picture gives an overview of all tanks not related to cargo

operations like HFO, DO, FW and forepeak/aftpeak tanks.

The picture displays both a layout of the tanks as well as an ullage bar graph shown in %.

These tanks can be manually filled or emptied in this picture.

A summary of the tanks will also be shown.

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3.5.4 Shear Force

The Shear Forces are calculated from the load distribution of the ship including the steel

weights of the different hull sections, and the corresponding buoyancy forms.

The graphic picture will display three different curves: yellow shows maximum permitted

shear forces in harbour condition; red curve the maximum permitted shear forces in

seagoing condition and the blue curve is the actual shear forces.

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3.5.5 Bending Moment

The Bending Moments are calculated from the Shear Forces. The actual bending moment

curve is drawn in blue, the yellow and red curves give maximum limits for respectively

harbour and seagoing condition.

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3.5.6 Deflection

The hull´s deflection (from the straight line) is calculated from the bending moments and

from the elasticity of each hull section. Positive deflection represents a hogging hull

condition, negative deflection represents a sagging hull condition.

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3.5.7 Stability

The stability curve in the form of righting arm values is calculated for heel angles ranging

from 0 to 60 degrees. All righting arm values are corrected (reduced) for possible "free

surface" effects. The reduction in meta centric height is specifically given.

The area under the stability curve represents the heel resistance or dynamic stability.

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3.5.8 Shore Tanks

The Shore Tanks picture gives an overview of the shore tanks which we can load from or

discharge to. There is two shore tanks. Note also the Emergency Shutdown Button in the

lower right corner.

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3.5.9 Ship/Shore Connection

Ship/Shore connection shows the shore and the vessel manifold. Shore has two liquid

manifolds and two vapour manifolds. It also indicates a lightering barge/vessel which can

be used.

The manifold all the way to the left in the picture is a ballast discharge manifold on the

vessel and the ballast receiving manifold on the shore side.

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Manifolds

There are four liquid cargo manifold connections, and one vapour line connection on each

side.

But as you can see there is also a thin white nitrogen line connected to the liquid and

vapour lines for inerting of the latter. There are also several measuring points in this

picture shown by the SP buttons. By clicking on one of these a multi-meter is presented:

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.10 Deck Lines

All tanks are connected to the same mainlines onboard, but divides into four tanks in one

end and four manifolds in the other end. There is only one vapour line and manifold

connection.

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3.5.11 Cargo Tanks

There are four tanks. We use tank no 1 as an example here. We have a view of the two

cargo pumps and one spray pump and the position were the emergency pump can be

installed. From the two cargo pumps there is a discharge line connected, each line with a

discharge valve. These lines are then merged into one common line. A filling line is also

shown to the right of the two discharge lines. A vapour line is connected as well. From the

spray pump there is a line going onto the main deck as well as a pipe going back to the tank

and dividing into the two spray line nozzle systems. Control of the cargo pumps and spray

system can be found to the right, where there are four PID controllers. Vital info on the ship

and the tank/cargo is shown to the left. An Emergency Shutdown button is shown in the

lower right corner. A picture of the ship at the lower left makes it possible to quickly

change the picture to one of the other cargo tanks by just clicking at the corresponding area

of the small ship.

Buttons with picture numbers make it possible to quickly change to other pictures in the

simulator.

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3.5.12 Cofferdams

There are five cofferdams although there are only four tanks. The first question that arises

is why do we have cofferdams between the cargo tanks? The reason is quite obvious when

we know a little more. The ship is basically built of ordinary steel. This material becomes

very brittle when cooled down to the temperatures we are talking about for this cargo. If

there were no cofferdams between the cargo tanks, the temperature from the cargo would

also reach the hull structure between the tanks. This would not work, and the hull would be

damaged. Therefore there is a built in heating system in the cofferdams which keeps the

temperature at a value of +5ºC. The heating system is required to manage a minimum of

0ºC under the most critical conditions!

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.13 Insulation Spaces Pressure Controller

This ship has two insulation barriers, and since the membrane in these barriers are very

thin and can not take two much pressure, there is a pressure control system fitted.

The system will also make sure the barriers are free of oxygen/methane whenever needed

by use of the vacuum pumps and the nitrogen supply.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.14 Compressor Room

This picture gives us an overview of the compressor room, consisting of the H/D and L/D

compressors as well as the heaters (L/D and H/D heaters) and vapourizers (LNG and

forcing vaporizer).

Connections are made to the deck lines as well as to the engine room (boiler supply).

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3.5.15 Low Duty System

The Low Duty System consists of the Low Duty compressors and the Low Duty heater.

The controllers for the L/D compressors are also in this picture, it will not be possible to

start the compressors unless the correct preparation is done. Which is to open for Nitrogen,

start the lub oil pump, open the suction inlet valve and the discharge valve and set the vane

angle to -80 deg. Only after getting the READY signal it will be possible to start the

system.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.16 High Duty System

The High Duty system consists of the H/D compressors and the H/D heater. The

controllers for the H/D compressors are also in this picture, it will not be possible to start

the compressors unless the correct preparation is done. Which is to open for Nitrogen, start

the lub oil pump, open the suction inlet valve and the discharge valve and set the vane

angle to -80 deg. Only after getting the READY signal will it be possible to start the

system.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.17 Vapourizers

Under the page of “Vapourizers” we will find the Forcing vaporizer and the LNG

vaporizer as well as a schematic picture of the L/D and the H/D compressors. This is only

to be able to look more into detail on the vapourizers which are positioned in the

Compressor room.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.18 Nitrogen Plant

The Nitrogen plant consists of two Nitrogen compressor systems delivering Nitrogen

supply to the ship wherever needed.

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3.5.19 Inert Generator

The cargo handling simulator is modelled with an inert gas plant where HFO is burned

effectively and the exhaust gas is directed through the scrubber to the main inert gas deck

line. The capacity of the inert gas plant is approximately 5000 m3/h. The scrubber washes

and cools the flue gas in order to reduce soot and SO2 content.

The inert gas plant is fitted with two air inlets, one for each fan, allowing the plant to take

air instead of inert gas for ventilating and gas-freeing cargo tanks.

The drier unit consists of two units: the refrigerating/cooling unit and a drier unit

containing activated alumina. They are in this model fully automated.

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3.5.20 Ballast Tanks

All ballast tanks are situated in the double bottom. They give a graphic view of the content

of the different tanks as well as the sounding. All connections between the tanks with lines

and valves are shown. In addition we are also given the trim, list and draft measurements.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.21 Ballast Pump Room

The ballast pump room picture shows a schematic view of the actual ballast pump room. In

this room there are three ballast pumps and an ejector.

These ballast pumps have a capacity of 3000 m3/h – 35 mTH (SW).

The ejector has a capacity of 300 m3/h – 20 mTH (SW).

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


3.5.22 H/D & Spray Control Panel

In this panel we are positioned in the cargo control room. We have the control panel for the

Cargo Tank Spray pumps and Spray Header (which are connected and work together) as

well as the control panel for the two H/D compressors positioned in the Compressor Room.

The Spray Sequences are started from these panels.

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


3.5.23 Cargo Control Panel

This is another part of the panels in the Cargo Control Room.

From these panels we control the cargo pumps start up, their changeover to discharge and

the temperature setter of the tank which is only used under a voyage.

The Automated Tank measurement system is also started from these panels (CTS).

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.24 Fixed Gas Detection System

This ship has a fixed gas detection system which runs all the time. It is divided in two

parts. The one to the left consists of one metering system which is measuring on 40

different locations onboard. Changing from one to the other automatically. When all 40 has

been checked the system starts from measuring point one again.

The other part to the right will measure in eight different locations continuously, so

whenever there is a gas-leak in these places there will be an immediate alarm.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.25 CCTV CAMERA

Via the MD page nr 140 you can get up the picture from the CCTV Camera.

You can see either the vessels manifolds or the vessel seen from the dock.

This can be chosen from buttons in the picture.

This is visualizing the connection/disconnection of loading arm or cargo hoses.

If there is a leakage in the manifold connection or blind flange this will also be visible.

Leakages can be triggered either from wrong procedure during disconnection or from a

malfunction set by the instructor.

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Doc.no.: SO-1295-D / 7-Jan-11


From the operation page which is accessed via the “F5” button it is possible to change the

operating scenario. “Weather scenario” and “Ship state” can be changed

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3.5.26 Picture Directory (Load Master)

The purpose of the Load Master Computer is to avoid excessive bending stresses in the hull

structure by offering the stress calculations off-line in advance. These stresses vary with the

cargo distribution throughout the length of the ship. Incorrect loading can damage the ship

and hence the cargo/ballast must be placed according to a carefully calculated plan.

Standard plans are often prepared by the shipyard.

However, it is impossible to foresee all cargo distributions, it is therefore necessary to have

a sophisticated calculator on board which can provide all the appropriate stresses for every

load distribution case which is manually input.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.27 Load Master Cargo Tank Overview

From this picture it is possible to try out various tank settings, and it does not matter

wether you put in the sounding, the volume (in %) or the mass of the cargo. The load

master will do the right calculation anyway. The corresponding trim and list will change

accordingly.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.28 Load Master Ballast Tank Overview

Here you may have a look at the different values of the ballast tanks shown as bar graphs.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.29 Load Master Bunker/Consumables

All consumables may be entered here in a simple way, and the trim and list will change

accordingly. This makes it easy to try out and plan a stowage for a trip.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.30 Load Master Shear Forces

This picture shows the actual shear forces which will affect the ship in this situation. This

makes it possible to check if the wanted condition is suitable for the ship or not.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.31 Load Master Bending Moment

This picture shows the actual bending moments which will affect the ship in this situation.

This makes it possible to check if the wanted condition is suitable for the ship or not.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.32 Load Master Deflection

This picture shows the actual deflection which will affect the ship in this situation. This

makes it possible to check if the wanted condition is suitable for the ship or not.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.33 Load Master Stability

This picture shows the actual stability of the ship in this situation. This makes it possible to

check if the wanted condition is suitable for the ship or not.

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3.5.34 Description of Legends

In this diagram an explanation is given of all colours, symbols and abbreviations used in

the various mimic diagrams throughout the system.

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Doc.no.: SO-1295-D / 7-Jan-11


3.5.35 Seek tag Functionality

All valves, pump, flows etc in the simulator do have a tag. Consisting of a ‘Capital’ letter

and some numbers. IE: V31756 is a discharge valve in one simulator model.

If you know the Tag name, you can seek for the Tag by pushing “CTRL” + “T”

When typing the tag name and enter, you will be directed to the first page were the

mention tag is present.

If you type a TAG name which not exists, the text “Tag not found” will be displayed in the

bottom of the screen.

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Doc.no.: SO-1295-D / 7-Jan-11


4. OPERATION OF THE LNG MEMBRANE TANKER

4.1 Introduction

This Chapter describes the cargo handling principles and operations relevant to the

simulator. But please be aware that the manual is based on a real vessels manual, so there

might be some functions which is mention but do not exist in the manual!

The normal cycle of tanker operations comprises loading/deballasting, laden voyage,

discharging/ballasting, ballast voyage and reloading.

Loading is accomplished by following directions given in the ship's loading orders.

Discharging is accomplished by discharging the cargo directly into a terminal tank storage

area.

Ballasting is a process whereby sea water is taken aboard into the segregated ballast tanks

to ensure proper stability, propeller immersion and to provide good manoeuvring and sea-

keeping characteristics.

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Doc.no.: SO-1295-D / 7-Jan-11


4.2 Insulation Space Tests

4.2.1 In Service Tests

Classification society regulations require that the barriers of a membrane tank should be

capable of being checked periodically for their effectiveness.

The following covers the practice, recommendations and the precautions which should be

taken during the in-service periodical examination of the primary and secondary

membranes.

Caution

Measurement devices which may otherwise be damaged should be isolated prior to the

commencement of the test. The barrier spaces must at all times be protected against over

pressure, which might otherwise result in membrane failure.

4.2.2 Method for Checking the Effectiveness of the Barriers

Primary Membrane

Since each primary insulated space is provided with a permanently installed gas detection

system capable of measuring gas concentration at intervals not exceeding thirty minutes,

any gas concentration in excess, with regard to the steady rates, would be the indication of

primary membrane damage. It results that each primary membrane is, in terms of tightness,

continuously monitored and a special test would not be required to check its effectiveness.

However that may be, each primary membrane can be tested according to the method

described below for the secondary membrane.

Secondary Membrane

In order to check its effectiveness, the secondary (or primary) membrane is submitted to a

global tightness test, which is the reiteration of the equivalent test, carried out during the

cargo containment building.

Procedure

a) Reduce the insulated space pressure at the back of the membrane to be tested to 200

mbarA.

b) After a stabilising period of about 8 hours, record by means of an accurate measuring

device, the vacuum decay over the next 24 hour period.

c) From the results obtained, the selection of the 10 hours continuous period during

which the temperature variations of the compartments surrounding the tested

membrane are minimum.

d) The allowable limit for vacuum decay of the space is given by the equation:

Δp≤0,8

e

where e = the thickness in meters of the insulated space at the back of the membrane.

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4.2.3 In Service Global Tightness Test

The global test is carried out either during a maintenance period, or when the cargo tanks

have been warmed up and gas freed.

To overcome any doubtful results arising from possible leaks through equipment connected

with the insulated spaces i.e. valves, pressure relief valves, electric cable glands etc, their

effectiveness must be carefully checked, and eventually replaced with blank joints, in so

far as the spaces remain protected against any over-pressure.

Test of Secondary Membrane

a) The pressure of the secondary space is reduced to 200 mbarA, while the primary

space is maintained at a slight vacuum.

(i.e. -100 mbar)

Under these conditions, the secondary membrane is submitted by one side to the

atmospheric pressure existing inside the primary space, by the other to the reduced

pressure existing inside the secondary space.

b) The vacuum decay is carried out on this space only by the method described in

secondary membrane testing b), c) and d).

In spite of the precautions taken for providing against leaks of the equipment, it is

important to check whether the vacuum decay of the secondary barrier space (DPs)

corresponds with a pressure reduction of the primary space (DPp).

If this is not the case, there may be an external leak which must be located and rectified

before another test is conducted.

When comparing (DPp) and (DPs), it is necessary to take into account the primary and

secondary space volumes as shown in the equation below:

ΔPρ=

ΔPxes

ep

Where (es) and (ep) represents the thickness of the secondary and primary spaces.

Primary Membrane Test Procedure

a) The pressure of the primary and secondary barrier spaces is reduced to 200 mbar a

simultaneously, in communication, in order to prevent the potential collapse of the

secondary barrier due to a higher pressure than that of the primary space.

b) The primary and secondary spaces are isolated and the vacuum decay procedure is

followed on the primary space only. The method used is as described in secondary

membrane testing b), c) and d).

Under these conditions, the primary membrane is submitted by one side to the atmospheric

pressure existing inside the tank and by the other to the reduced pressure existing inside the

primary space.

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Since both faces of the secondary membrane are in an equal pressure system, no flow can

be generated through any eventual leak of this membrane; therefore the measured vacuum

decay is the correct figure of the tightness of only the primary membrane.

Caution

Changes in temperature or barometric pressure can produce differentials far in excess of

30 mbar in the insulation spaces which are shut in. With the cargo system out of service

and during inerting, always maintain the primary insulation space pressure at or below

tank pressure and always maintain the secondary insulation space pressure at or below the

primary insulation space pressure. Severe damage to the membranes may occur if the

differentials exceed 30 mbar.

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Doc.no.: SO-1295-D / 7-Jan-11


4.3 Post Dry Dock Operation

4.3.1 Insulation Space Inerting

4.3.1.1 First Step: Evacuation of Insulation Space

Caution

To avoid major damage to the secondary barrier, never evacuate a primary insulation

space whilst leaving the associated secondary space under pressure and never fill a

secondary space whilst the primary space is under vacuum.

Prior to putting a cargo tank into service initially, or after dry docking, it is necessary to

replace the ambient humid air in the insulation space with dry nitrogen.

This is done by evacuating the insulation spaces with the vacuum pumps and refilling them

with nitrogen. The procedure is repeated until the oxygen content is reduced to less than

2%.

Evacuation of all the insulation spaces takes approximately 8 hours. Three cycles are

usually necessary to reduce the oxygen to less than 2% by volume.

Caution







Before refilling with nitrogen, the insulation spaces arc evacuated to 200 mbar absolute

pressure. The evacuation of the insulation spaces is also used in order to check the integrity

of the barriers during periodical test.

To avoid possible damage to the secondary membrane, the secondary insulation spaces

must be evacuated before the primary insulation spaces. The pipe work at the vacuum

pump's suction has been designed to ensure that the evacuation of the primary spaces

cannot take place without having first evacuated the secondary spaces, or ensuring that

they will be both evacuated simultaneously.

Two electrically driven vacuum pumps, cooled by fresh water, are installed in the cargo

compressor room. They draw from the pressurisation headers and discharge to the vent

riser No.2.

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Doc.no.: SO-1295-D / 7-Jan-11


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Doc.no.: SO-1295-D / 7-Jan-11


Operating Procedure All valves are assumed shut. – All valves mention in this procedure is on MD 240

a) Isolate any pressure gauge, transducer or instrument which could be damaged

by the vacuum and install temporary manometers to allow pressures in the

insulation spaces to be monitored.

b) On each tank, open Second.Ins. Space valves (V24014, V24013, V24012 and

V24011) connecting the pressurisation header with the feeder columns of the

secondary insulation spaces.

c) Open the S.Ins.Space.Head to Vacuum pumps Vlv (V24054) and Nitrogen to

Vacuum pump Vlv (V24053), and vacuum pumps suction valves

(V24051&V24052)

d) Prepare the vacuum pumps for use.

e) Start both vacuum pumps.

f) Monitor the secondary insulation space's pressure. When it has been reduced to

200 mbarA, in all the spaces, stop the pumps.

g) Close Second.Ins. Space valves (V24014, V24013, V24012 and V24011) on

the trunk deck.

h) On each tank, open the Primary Ins.Space Valves (V24004, V24003, V24002

& V24001) connected to the pressurisation header with the aft transverse of the

primary insulation spaces.

i) Open the Primary Ins. Space Header to Vacuum valve (V24055)

j) Start both vacuum pumps.

k) Monitor the primary insulation spaces, pressure. When it has been reduced to

200 mbarA, in all the spaces, stop the pumps.

l) Close Primary Ins.Space Valves (V24004, V24003, V24002 and V24001) on

trunk deck.

m) Close valves V24054, V24053, V24055 and valves V24052, V24051 at the

pumps' suction.

n) Stop the vacuum pumps

During the evacuation of the insulation spaces, the tightness of the primary and secondary

insulation spaces relief valves has to be confirmed and if suspected of leaking, blanked

until the operation is completed. Blanks must be clearly marked and notices posted.

General notes on the vacuum pumps:

Ensure that auxiliary fresh water for auxiliary fresh water cooler is available and on.

Ensure that the LO tank is full and the power supply to the pumps is available.

Ensure that the bulkhead seal system is full.

Ensure that the pump is free to rotate.

Ensure that LO is feeding the lubrication points.

Close the pump drains.

(Some of these checkpoints are not possible to do in the simulator, but are kept to show the

full extent of the operation in real life).

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Doc.no.: SO-1295-D / 7-Jan-11


4.3.1.2 Second Step: Initial Filling with Nitrogen

After evacuation, the next step consists of filling the insulation spaces with nitrogen. The

cycle is repeated until the oxygen content in the spaces is less than 2%.

Procedure for Initial Filling With Nitrogen

Depending on the type of vessel there are several ways of supplying N2 to this operation.

Some vessels use liquid N2 supplied from shore to the liquid manifold where it passes to

the stripping/spray header via the appropriate ESDS liquid valve. It is then fed to the LNG

vaporizer and N2 gas produced is passed at +20°C to each insulation spaces.

At this stage, ship's N2 generators are not used due to required capacity for initial filling.

Other vessels use N2 storage tanks to supply the N2 necessary to carry out the operation.

We have chosen to go for the latter version.

It is assumed that all valves are closed prior to use. All valves for below procedure is on

MD 240

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Doc.no.: SO-1295-D / 7-Jan-11


a) Line up from the Nitrogen storage tank. Open Nitrogen supply & reduction valves

V24041, V24042, V24043, V24044 & the Nitrogen Supply Cross over Vlv(V24045)

and Nitrogen main supply Vlv (V24046).

b) Open the nitrogen supply isolation valves (V24027, V24026, V24025 and V24024).

c) Open the Primary & Secondary Exhaust Isolation valves (V24034, V24035, V24036

and V24037).

d) On each tank open the primary space supply valves (V24004, V24003, V24002,

V24001).

e) Adjust the opening of the primary space supply valves for balancing the pressure rise

in all the spaces. In the Simulator they are not adjustable, only open or closed.

During filling, always maintain the pressure in the primary space 100 mbar above the

secondary space.

f) When the pressure in the primary spaces reaches 300 mbarA (100 mbar above the

pressure in the secondary spaces), on each tank open the secondary space supply

valves (V24014, V24013, V24012, V24011). Adjust the opening of these valves for

balancing the pressure rise in all the spaces.

g) Set the controller for the Primary & Secondary space Exhaust valves (V24031 &

V24032) at 4 mbar (0,4 kPa).

Operating Procedure for the Completion of the Nitrogen Filling

a) The final filling of the insulation spaces, up to 2 mbar is carried out at reduced flow

rate. Three cycles are usually necessary.

b) After the final filling, check the oxygen content in all the spaces. If it is higher than

2%, repeat inerting operation. There is also the possibility to check the 02 content at

the vacuum pump discharge.

Caution







Operating Procedure for Normal Inerting

The primary and secondary insulation spaces are filled with dry nitrogen gas which is

automatically maintained by alternate relief and make-up as the atmospheric pressure or

the temperature rises and falls, under a pressure of between 2 mbar and 4 mbar above

atmospheric.

The nitrogen provides a dry and inert medium for the following purposes:

To prevent formation of a flammable mixture in the event of an LNG leak

To permit easy detection of an LNG leak through a barrier

To prevent corrosion

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Excess nitrogen from the insulation spaces is vented to mast No.2, through the exhaust

regulating valves.

Both primary and secondary insulation spaces of each tank are provided with a pair of

pressure relief valves which open at a pressure, sensed in each space, of 10 mbar above

atmospheric. A manual bypass with a cut out valve and a ball valve is provided from the

primary space to the N2 vent mast for local venting and sweeping of a space if required.

The nitrogen production is maintained in an automatic mode.

a) Adjust the set point of the nitrogen supply regulating valve (V24021) –MD240 to the

secondary header at 2 mbar/0,2 kPa, and the regulating valve (V24022) to the

primary header at 2 mbar/0,2 kPa.

b) At the forward part of the trunk deck, ensure that the Primary & Secondary space

Exhaust Isolating valves (V24034, V24035, V24036 and V24037) are open.

c) Adjust the set point of the Pri.Nitrogen exhaust control valve (V24031) at 4

mbar/0,4 kPa and regulating valve (V24032) (secondary) at 4 mbar/0,4 kPa.

There is a standby exhaust regulating valve (V24033), which can be connected to either the

primary or secondary system in the event of failure of one of the master regulating valves.

The nitrogen supply to the insulation spaces has a standby regulating valve V24023, which

can be connected to either the primary or secondary system in the event of failure of one of

the master regulating valves.

In the event of cargo gas leakage into insulation spaces, this can be swept with a

continuous feed of nitrogen by opening the exhaust from the space, allowing a controlled

purge. Close monitoring of the gas analyser on this space will be necessary during purging.

In cases where other consumers reduce the availability of nitrogen for the insulation

spaces, the pressure may temporarily fall below the atmospheric pressure.

This condition is not critical insofar as the differential pressure (Ps - Pp) between the

secondary spaces pressure (PS) and the primary space pressure (Pp) do not exceed 30

mbar/3 kPa.

(Ps - Pp) < 30 mbar

Warning

When the depression in the primary insulation spaces, relative to the secondary insulation

spaces, reaches 30 mbar, the two insulation spaces shall be immediately inter-connected -

which will involve a manual operation.

When put in communication, and therefore subjected to the same nitrogen pressure, the

primary and secondary insulation spaces can withstand a large depressurisation without

any damage.

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Doc.no.: SO-1295-D / 7-Jan-11


It should be noted that, even with the tanks fully loaded, a pressure lower than atmospheric

pressure in the primary insulation spaces is not harmful to the primary membrane. In this

respect, it should be noted that this membrane is subjected to a -800 mbar vacuum pressure

- both during global testing at the construction stage and also for the insulation spaces'

cycles purging.

4.3.2 Drying Cargo Tanks

During a dry docking or inspection, cargo tanks which have been opened and contain

humid air must be dried to avoid primarily the formation of ice when they are cooled down

and secondly, the formation of corrosive agents if the humidity combines with the sulphur

and nitrogen oxides which might be contained in excess in the inert gas. The tanks are

inerted in order to prevent the possibility of any flammable air/LNG mixture. Normal

humid air is displaced by dry air. Dry air is displaced by inert gas produced from the IGG.

Dry air is introduced at the bottom of the tanks through the filling piping. The air is

displaced from the top of each tank through the dome and the vapour header, and is

discharged from the vent mast No. l.

The operation is carried out when in port or at sea and it will take approximately 20 hours

to reduce the dew point to less than -20°C.

At the same time that the inert gas plant is in operation for drying and inerting the tanks,

the inert gas is also used to dry (below -40°C) and to inert all other LNG and vapour pipe

work. Any pipe work not purged with inert gas must be purged with nitrogen before the

introduction of LNG or vapour.

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Doc.no.: SO-1295-D / 7-Jan-11


Operating Procedure for Drying Tanks

Dry air, with a dew point of -45°C, is produced by the IGG at a flow rate of 14,000 Nm3/h.

a) Prepare the dry air/inert gas plant for use in the dry air mode (the burner is not

started) See IGG Plant operating Instruction Chapter 2.4.18.

b) Open blind flange Hold Gas Free Line/Liquid Line(F12001)-MD121 to connect the

inert gas/dry air feeder line to the liquid header.

In MD121: Open valve Vapour/Inert Gas to Liq Head (V12702), in cgo tank Pictures

1-4 open:

CT 1 Liquid Filling Vlv (V20100) and CT 1 Liquid Isolation Vlv (V20110)-MD201




to supply dry air to the liquid header.

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Doc.no.: SO-1295-D / 7-Jan-11


c) Open the individual tank dome vapour header valves.

CT 1 Vapour Valve (V20170)-MD201




d) Go to MD330 and use the vent control panel to open the Vapour Header Vent Ctrl

Vlv (V12771) (push MAN and set the value to 100%).

e) Go to MD 121, open the Vapour Head Vent Shut off Vlv (V12772) to vent through

the No.1 vent mast. Manually regulate the tank pressure by regulating valve V12771

at MD330. The pressure should not be higher than 10 kPa.

f) Start the dry air production. When the dew point after the drier is -45°C (X35044),

open the valve IG Main Line Supply Vlv 2 (V35042)-MD350 upstream of the two

non-return valves on the dry air/inert gas discharge line.

g) Monitor the dew point of each tank by taking a sample at the vapour domes. When

the dew point is -25°C or less, close the filling and vapour valves of the tank.

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Humid air which may be contained in the discharge lines from the cargo pumps, float level

piping and any associated pipe work in the cargo compressor room must be purged with

dry air.

h) When all the tanks are dried, stop the plant. Remove the Hold Gas Free Line/Liquid

Line flange (F12001) and close the Vapour/Inert Gas to Liq Head supply valve

(V12702) to the LNG header and close the Vapour Head Vent Shut off Vlv (V12772)

to the venting system at the mast riser No. l.

Note It is necessary to lower the tank's dew point by dry air to at least -20°C, before feeding

tanks with inert gas in order to avoid formation of corrosive agents.

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Doc.no.: SO-1295-D / 7-Jan-11


4.3.3 Inerting Cargo Tanks

Inert gas, with an oxygen content of less than 1% and a dew point of -45ºC, is produced by

the IGG with a flow rate of 14,000 m3/h. The inert gas is primarily nitrogen and carbon

dioxide, containing less than 1% oxygen with a dew point of -40°C or below.

Emergency pump wells have to be inerted with nitrogen before inerting the cargo tanks.

(Inerting of emergency wells are not part of the simulator).

Warning

Inert gas from this generator and pure nitrogen will not sustain life. Great care must be

exercised to ensure the safety of all personnel involved with any operation using inert gas

of any description in order to avoid asphyxiation due to oxygen depletion.

a) Prepare the IGG for use in the inert gas mode. See IGG Plant operating instructions

chapter 2.4.18.7

b) Open blind flange Hold Gas Free Line/Liquid Line(F12001)-MD121 to connect the

inert gas/dry air feeder line to the liquid header.

c) Open the Vapour/Inert Gas to Liq Head Vlv (V12702), open:





to supply inert gas via the liquid header to the cargo tanks.

d) Open the individual tank dome vapour header valves.





e) Go to MD330 and use the vent control panel to open the Vapour Header Vent Ctrl

Vlv (V12771) (push MAN and set the value to 100%).

f) In MD 121, open the Vapour Head Vent Shut off Vlv (V12772) to vent through the

No.1 vent mast. Regulate the tank pressure by regulating the Vapour Header Vent

Ctrl Vlv (V12771)-MD330. The pressure should not be higher than 10 kPa.

g) Start the inert gas production. When oxygen content is less than 1% and dew point is

-45ºC, open IG Main Line Supply Vlv 2 (V35042)-MD350 upstream of the two non-

return valves on the inert gas discharge line.

h) By sampling at the vapour domes, check the atmosphere of each tank by means of

the portable oxygen analyser. O2 content is to be less than 2% and the dew point less

than -40°C.

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Doc.no.: SO-1295-D / 7-Jan-11


i) During tank inerting, purge for about 5 minutes the air contained in the lines and

equipment by using valves and purge sample points (not fitted in the simulator).

j) When the inerting of the tanks, lines and equipment is completed, regulate Vapour

Header Vent Ctrl Vlv (V12771)-MD330, so that all the tanks are pressurised to 15

kPa.

k) When the operation is completed, stop the supply of inert gas and close the IG Main

Line Supply Vlv 2 (V35042)-MD350, close the Vapour/Inert Gas to Liq Head Vlv

(V12702)-MD121 close the Hold Gas Free Line/Liquid Line blind flange (F12001)-

MD 121. An then close on the cargo tanks:





Note Until the ship is ready to load LNG for gas filling, the tanks may be maintained under inert

gas as long as necessary. If required pressurise the tanks to 20 mbar/ 2 kPa above

atmosphere pressure and, to reduce leakage, isolate all the valves at the forward venting

system.

The inert gas is purged and replaced by natural gas (NG) produced by the LNG vaporizer

(+20ºC outlet temperature) fed with LNG supplied by the loading terminal. One point eight

(l,8) complete volume changes are required for displacing the inert gas and attaining a CO2

content ≤ 1% by volume. This operation is complete in 20 hours.

4.3.4 Gassing-up Cargo Tanks

Introduction

After lay-up or dry dock, the cargo tanks are filled with inert gas or nitrogen. If the purging

has been done with inert gas, the cargo tanks have to be purged and cooled down when the

vessel arrives at the loading terminal. This is because, unlike nitrogen, inert gas contains

15% carbon dioxide (CO2), which will freeze at around -60°C and produces a white

powder which can block valves, filters and nozzles.

During purging, the inert gas in the cargo tanks is replaced with warm LNG vapour. This is

done to remove any gases which can freeze, such as carbon dioxide, and to complete the

drying of the tanks.

Description

LNG liquid is supplied from the terminal to the liquid manifold where it passes to the

stripping/spray header via the appropriate ESDS liquid valve. It is then fed to the LNG

vaporizer and the LNG vapour produced is passed at +20°C to the vapour header and into

each tank via the vapour domes.

At the start of the operation to fill the cargo tanks, the piping system and LNG vaporizer

are vapour locked. The stripping/spray header can be purged into the cargo tanks via the

vapour dome through the arrangement of spray valves containing the control valve until

liquid reaches the LNG vaporizer. The LNG vapour is lighter than the inert gas, which

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Doc.no.: SO-1295-D / 7-Jan-11


allows the inert gases in the cargo tanks to be exhausted up the tank filling line to the liquid

header. The inert gas then vents to the atmosphere via the No. l vent mast.

When 5% methane (the percentage figure will be specified by the particular port authority)

is detected at No.1 vent mast riser, the exhaust gas is directed ashore via the HD

compressors by-pass line, or to the boilers through the gas burning line.

This operation can be done without the compressors, subject to existing back pressure, or

with one or both HD compressors in service. If possible, it is better not to use compressors

to avoid creating turbulence inside the tanks.

The operation is considered complete when the CH content, as measured at the top of the

cargo filling pipe, exceeds 98% by volume.

The target values for N2 gas and inert gas CO2 is equal or less than 1%. These values

should be matched with the LNG terminal requirements.

This normally entails approximately 2.0 changes of the volume of the atmosphere in the

cargo tank.

On completion of purging, the cargo tanks will normally be cooled down.

There are exceptional cases where it may be necessary to undertake the purging of one or

more tanks at sea using LNG liquid already on board. In this case the liquid will be

supplied to the LNG vaporizer via the stripping/spray header using the stripping/spray

pump of a cargo tank containing LNG liquid. Due to local regulations on venting methane

gas to the atmosphere, some port authorities may require the entire operation to be carried

out with the exhaust gases being returned to shore facilities.

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Operating Procedures to Purge the Cargo Tanks with LNG Vapour.

Stage One

It is assumed, though unlikely, that all valves are closed prior to use. The vessel is docked

with port side to and the 3P manifold is connected, purged and ready.

l) Install the following spool pieces:

Liquid line –Vapour Line Flange F12002 (MD 121)header to compressors (only if

compressors are required),

Vapour Line - Liquid Line Flange F12000 to No.1 vent mast (MD121)

m) Prepare the LNG vaporizer for use. (MD 329), open the LNG Vapourizer steam inlet

valve (V32970) to supply heat to the vaporizer and set capacity to 100%. Then open

the LNG Vapourizer Flow Control Valve (V32901)

n) Adjust the set point of the output temperature controller(Z32910) . This regulates the

Temp Ctrl. Valve(V32902) to +20°C.

o) Regulate the tank pressure by regulating valve V12771 at MD330. The pressure

should not be higher than 60 mbar/6 kPa (or required value).

p) At No.1 vent mast, open the Vapour Head Vent Shut Off Vlv (V12772) MD 121

q) Open valve the LNG Vapourizer Supply Vlv (V12056) MD 121, to the manifold.

Open the Vapour/Inert Gas to Liq. Head Vlv (V12702)

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r) In the cargo machinery room (MD300 or MD 329 open LNG Vaporizer Outlet Vlv

(V32918).

s) Open the LNG/Vap/Vapour Head Conn. Vlv V30605(MD 300) to supply vapour

from the vaporizer to the vapour header.

t) Open the individual tank dome vapour header valves.





For safety reasons, ensure that the hull water curtain on the connected side is in operation.

The water curtain is not shown in the manifold pictures but there is a Water Spray Disch.

Vlv (V40144) to the system in the ballast pump room picture - MD401

u) Open Liq. Manif. Cooldown Vlv (V12065) -MD120 or MD121(if using the after

liquid manifold on the port side), or the Starboard Liq. Manif . Vlv (V12066)-MD

120 (if you are using the starboard side), the isolating valve to the LNG vaporizer

supply line.

v) Open the individual tank dome liquid filling & liquid isolating loading valves.





w) Open the Liq. Manif 3P ESD Vlv (V12031)-MD 120 or MD 121, the liquid

manifold valve on the port side. Request the terminal to commence supply of

LNG liquid to the ship at a constant pressure of 2 bar/200 kPa.-MD110. (Start

up the shore side pump with the liquid loading rate set at 10% capacity. Open

the Shore Tank Isolation Valve (V11002) and Shore Line 3 Shut Off Valve

(V11031)-MD110

x) Set the controller at No. 1 vent mast to AUTO this will control the Vapour Head.

Vent.Ctrl Vlv (V12771)-MD 330. The Automatic set point is at 230 mbar/23 kPa .

y) Monitor the inert exhausting gas at each liquid dome. Also monitor the inert

exhausted gas at No.1 vent mast by using the sample point at MD 201(upper right

corner)

z) When 5% methane, (or the quantity the port authority will allow) is detected at No.1

vent mast and at each vapour dome, request permission from the terminal personnel

to direct exhaust gas to the terminal facilities. Verify that your Vapour Manif. P Flange to Shore is connected and OPEN.

Shore side should open the Shore Vapour Line Shut off Valve (V11071) and Flare

Vapour Return Valve (V11073)-MD 110, each 100%.

At the manifold, fully open the Vapour Manif. P ESD Vlv (V12071)-MD121

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Finally, fully open (100%) the Vapour Crossover Block Valve(V12079)-MD121.

The vapour from the tanks now has a path to shore.

Close the Vapour Header Vent Shut Off Vlv (V12772) and the Vapour Header Vent

Control Vlv (V12771)-MD121. This will secure shipboard venting.

aa) Now you can safely remove the spool piece installed between Liquid main and

Vapour Main line (F12000)-MD121.

Natural Gas Total Required

1.8 x 145.914 m3 (100% of Total Volume) = 262.646 m3 OF NG

Required LNG

LNG Total Requirement = 1,8 x V(100 %) x ρ NG

= 1,8 x 145.914 x 0.8120

= 213.268,6 kg

= 454,7 m3 of LNG

(Density ρ NG = 0.8120 kg/m3 AT +20ºC and 1,060 mbara)

Required Heat Energy at Initial Purging

Tank Tk Volume

(m3)

Required

NG (m3)

Required

LNG (kg)

Required

LNG (m3)

Heat Energy

(MMBTU)

No.1 21958 39524,6 32094,0 68,4 1649,6

No.2 43049 77487,8 62920,1 134,2 3234,1

No.3 43049 77488,9 62921,0 134,2 3234,1

No.4 37858 68144,8 55333,5 118,0 2844,1

Total 145914 262646,1 213268,6 454,7 10962,0

Note

I) LNG Density: 469,0 kg/m3

2) LNG Heating Value: 51,400 MMBTU/ton

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Doc.no.: SO-1295-D / 7-Jan-11


Stage Two

Inert gas condition CO2: equal to or less than 1%.

Nitrogen gas condition N2: equal to or less than 1%.

When 5% CH content (or the quantity of port authority is allowed) is detected at No.1 vent

mast and each vapour dome, request permission from the terminal personnel to direct

exhaust gas to the terminal facilities as flare stack.

Normally HD compressor shall not be used to avoid creating turbulence inside the tanks.

Cargo tank pressure shall not be maintained in steady condition due to the back pressure

from shore side; in that case the HD compressor shall be used for the operation.

a) Prepare both HD compressors for use. See Chapter 2.4.8

b) Install the spool piece connecting the liquid line to the suction for the HD

compressors (F12002)-MD121

c) On the HD compressors (MD 319)open the following valves:

Inlet to No.1 HD compressor (V31907)

Outlet from No. l HD compressor (V31909)

Inlet to No.2 HD compressor (V31910)

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Outlet from No.2 HD compressor (V31912)

d) Open the following valves:

Open the Vapour/Inert Gas to Liq. Head Vlv (V12702)-MD 121, and Hot Vapour

Compressor suction Vlv (V30603)-MD 300 and the Vapour return Throttling Vlv

(V31900)-MD300, compressor supply to the manifold.

e) Open the vapour manifold ESD valve (V12071)- port side MD120 or MD121. This

will enable a free flow of gas to the terminal and is a check that the pipeline layout

on board has been arranged correctly.

f) Make sure the lube oil is started, there is N2 supply to the compressor, and that the

vane is set to -80 to get “Start available”. Start the compressors and adjust the

pressure set point of both HD compressors’ flow control, to around 6-7 kPa.

g) Once the flow to the terminal has been established, close the Liq.Head to No 1 Vent

Mast Vlv (12000)- MD 121. Close the No.1 mast riser control valve (V12771)-MD

330, and open the Vapour Header Vent Shut Off Vlv (V12772)-MD121.

h) If the tank pressure increases too much, start one or both of the compressors as

necessary.

i) Monitor the pressure inside the tanks.

If the pressure increases, request the terminal to reduce the supply of LNG, or increase the

flow through the HD compressor by adjusting the set point on both HD compressors to be

controlled by pressure set point.

If the pressure decreases, reduce the flow through the HD compressors by adjusting the set

point of both HD compressor's. Alternatively, shut down one of the compressors as

necessary, or request the terminal to increase the LNG liquid supply to the LNG vaporizer.

But normally HD compressors may not be used.

When the cargo tank CH content reaches 98%, throttle in the individual tank loading valve

until it is only just cracked open.

During the change of atmosphere, purge the following sections for about 5 minutes each:

a) All sections of the stripping/spray header and tank connections, via the valves at each

vapour dome:

CT.1 Spray By Pass Vlv(V20156), low & upper spray Vlv (V20151 & V20152)

CT.2 Spray By Pass Vlv(V20256), low & upper spray Vlv (V20251 & V20252)

CT.3 Spray By Pass Vlv(V20356), low & upper spray Vlv (V20351 &V20352)

CT.4 Spray By Pass Vlv(V20456), low & upper spray Vlv (V20451 &V20452)

b) Purge manual valves and ESD valves. The manifold bypass valves are not in use.

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The operation is considered complete when all four cargo tanks have at least a 98% CH

content and the acceptable CO2 content and/or N2 content as requested by the terminal.

c) Purge the following lines and equipment for five minutes each:

No.1 and 2 boil-off/warm-up heater, forcing vaporizer, (normal venting via the

sampling cocks, but these are not available in the simulator).

HD and LD compressors with the compressor inlet and outlet valves. Make

sure to thoroughly purge each compressor in turn.

Vapour crossover Starboard & Port manifold purge Valves (V12078 and

V12077)- MD120, venting through the manifold flanges (V12072 and

V12071).

Cargo pump lines, stripping/spray pump lines and emergency cargo pump well

via the appropriate line valve and purge sample point (no emergency pump

well or purge sample points on the simulator).

Extremities of vapour header via sample points (no sample points on the

simulator.

d) Request the terminal to stop the supply of LNG liquid.

e) Stop both HD compressors, if operated.

f) Close the LNG Vaporizer Supply Vlv(V12056)-MD 120 or MD 121, to isolate the

stripping/spray lines.

g) Do not shut down the LNG vaporizer until it has been warmed through to the

ambient temperature.

h) Remove any spool pieces after purging with nitrogen and testing the gas content.

i) Prepare the cargo system for cool down.

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4.3.5 Cooling Down Cargo Tanks

Introduction

Arriving at the loading terminal to load the first cargo after refit or when repairs require the

vessel to be gas free, the cargo tanks will be inert and at ambient temperature. After the

cargo system has been purge-dried and gassed up, the headers and tanks must be cooled

down before loading can commence. The cool down operation follows immediately after

the completion of gas filling, using LNG supplied from the terminal.

The rate of cool down is limited for the following reasons:

To avoid excessive pump tower stress.

Vapour generation must remain within the capabilities of the HD compressors to maintain

the cargo tanks at a pressure of 70 mbar/7 kPa (about 1083 mbarA).

To remain within the capacity of the nitrogen system to maintain the primary and

secondary insulation spaces at the required pressures.

Unlike rigid cargo tank designs, vertical thermal gradients in the tank walls are not a

significant limitation on the rate of cool down.

LNG is supplied from the terminal to the manifold cool down line and from there directly

to the spray header which is open to the cargo tanks. Once the cargo tank cool down is

nearing completion, the liquid manifold cross-overs, liquid header and loading lines are

cooled down.

Cool down of the cargo tanks is considered complete when the mean temperature except

two(2) top sensors in each tank indicate temperatures of -130°C or lower. When these

temperatures have been reached, and the CTS registers the presence of liquid, bulk loading

can begin. (GTT defines that target LNG loading is possible when mean temperature of the

cargo tank is lower than -80°C.) But GTT recommends to carry on the cool down operation

of the cargo tanks to -130°C as per LNG terminal requirement.

Vapour generated during the cool down of the tanks is returned to the terminal via the HD

compressors (or free flow) and the vapour manifold, as in the normal manner for loading.

During cool down, nitrogen flow to the primary and secondary spaces will significantly

increase. It is essential that the rate of cool down is controlled so that it remains within the

limits of the nitrogen system to maintain the primary and secondary insulation space

pressures between 2 mbar and 4 mbar (0,2 and 0,4 kPa).

Once cool down is completed and the build up to bulk loading has commenced, the lank

membrane will be at, or near to, liquid cargo temperature and it will take some hours to

establish fully cooled down temperature gradients through the insulation. Consequently

boil-off from the cargo will be higher than normal.

Cooling down the cargo tanks from +40°C to -130°C, over a period of 10 hours will

require a total of about 800 m3 of LNG to be vaporized. Cool down rate in the cargo tank

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and insulation spaces is depended on amount of spraying LNG. As typical data taken at gas

trial for the vessel refer to attached chart.

Preparation for Tank Cool Down

Place in service the heating system for the cofferdams.

a) Prepare the records for the tank, secondary barrier and hull temperatures.

b) Check that the nitrogen pressurisation system for the insulation spaces is in automatic

operation and lined up to supply the additional nitrogen necessary to compensate for

the contraction from cooling of the tanks. Prior to the cooling down, the nitrogen

pressure inside the primary insulation spaces will be raised to 6 mbar. Pressurise the

buffer tank at maximum pressure.

c) Check that the gas detection system is in normal operation.

d) Prepare the nitrogen generators for use.

Operating Procedure -Gas Return Through Vapour Header

Assume that the ship is ready to prepare for cool down after the completion of gas filling.

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As reported by several ship operators, it seems accepted that the vapour return through the

liquid header instead of the vapour header, makes the cool down operation more efficient

and prevents liquid droplets in the vapour stream. Alternatively, the procedure for cooling

down cargo tanks with gas return via the vapour header is as follows:

a) Arrange the nitrogen piping to preferentially feed the primary insulation spaces.

b) Adjust the set point of the nitrogen supply regulating valvesV24022(MD240), and

V24021 at 2 mbar/0,2 kPa.

c) Adjust the set point of the nitrogen exhaust regulating valvesV24032(MD240) and

V24031 at 4 mbar/0,4 kPa.

d) Open valve V12050 (MD 121)connecting the stripping/spray header with the forward

manifold and V12751, V12752, V12053 and V12055 on the stripping/spray header.

e) Open V12065(MD 120 or MD 121) to supply LNG from the liquid manifold.

f) At each vapour dome open the spray valves V20155, V20151, V20152,V20255,

V20251,V20252,V20355,V20351,V20352,V20455,V20451,V20452.

g) Open vapour valves on each tank:

h)




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i) At No.1 vent mast, open V12771(MD 330). Adjust the valve V12771 to keep at

pressure of 200 mbar/20 kPa.

j) Open the HD compressor's suction discharge and valves(V31907, V31909, V31910,

V31912) - MD319.

k) Open the HD compressor's suction from the vapour header V30601 (MD300)and

discharge valve V31900 (MD 300) to the vapour manifold.

l) Open vapour manifold valve V12071 (MD 121 or MD120)

m) When shore is ready to supply LNG, open ESDS valve V12031 ( MD 121 or

MD120)

n) After cooling down the lines, request the terminal to supply a pressure of 2 bar/200

kPa at the ship's rail. Monitor the tank's pressure and the cooling down rate.

o) Adjust the flow to the spray bars in order to obtain an average temperature fall of

20°C per hour in the first five hours and then 10-15°C per hour thereafter.

p) Start one HD compressor (or both as necessary) in order to maintain the tank

pressure at about 100 mbar/10 kPa.

q) Check the nitrogen pressure inside the insulation spaces. If it has a tendency to fall,

reduce the cooling down rate.

In cases where other consumers reduce the availability of nitrogen for the insulated spaces,

the pressure may temporarily fall below atmospheric pressure. This condition is not critical

insofar as the differential (Ps-Pp) between the secondary space pressure (Ps) and the

primary space pressure (Pp) do not exceed 30 mbar/3 kPa.

(Ps - Pp ≤30 mbar)

r) When the average of the temperatures shown by the sensors installed on the pump

towers is -130°C, request the terminal to stop LNG supply, and close V12031. The

other valves should remain open until the lines have warmed up.

s) Stop the compressor(s) if loading does not take place after cool down.

4.3.6 Spraying During Ballast Voyage

It is one of the operating schemes during ballast voyage.

After increasing cargo tank pressure, accumulated gas shall be used as fuel.

We assume that a single tank is to be cooled down, using heel from that tank.

It is assumed that all valves are closed prior to use, and we are using tank No.4.

Prepare the LD compressor(s) to supply the engine room with boil-off gas for the boilers.

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Make sure the pressure is 150 mbar/15 kPa by manually regulating of the forward mast

riser valve (V12771) at MD330.

Check the nitrogen system for high flow operation.

Confirm the set point of N2 supply regulating valve to 2 mbar/0,2 kPa.

Confirm the set point of N2 Exhaust regulating valve to 4 mbar/0,4 kPa.

a) Open vapour dome outlet valves to the vapour header:





b) Fully open the spray inlet valves to No.4 tank (V20451 and V20452). Partially open

the spray isolating valve (V20455) to the spray line - MD 204

c) Start No.4 spray pump and open the spray discharge valve (V20450 and V20455)

to allow minimum flow and to cool down the spray header. Pressure in stripping /

spray main line shall be controlled by the Spray Return Valve(V20454).

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d) Once cool down of the spray header to No.4 tank is complete, open up the Spray

Isolation Valve (V20455) and increase the flow rate by adjusting the spray pump

discharge valve to allow an even cool down and control of vapour pressure.

Care should be taken to maintain control of vapour pressure either by use in the boilers as

fuel, or venting to atmosphere via the forward riser.

e) On completion of cool down leave the spray header valves open to allow the spray

line to warm up to ambient temperature before closing them.

The above operation can be repeated for each individual tank.

4.3.7 Sloshing

Sloshing effect is not implemented in the simulator. From the experience gained on the

first LNG ships put into service and from a large number of model tests and computer

analyses, Gas Transport have designed new tanks which are reasonably free from any

sloshing risk.

The ship's cargo tanks are designed to limit the impact forces and the safety margin has

been considerably enlarged. However, operators should always be aware of the potential

risks to the cargo containment system and also on the tank equipment due to sloshing.

Precautions to Avoid Damage Due to Sloshing

Cargo tank levels:

The first precaution is to maintain the level of the tanks within the required limits i.e.:

Lower than a level corresponding to 10% of the length of the tank

Or

Higher than a level corresponding to normally 80% of the height of the tank.

Ship's movement:

The second precaution is to try to limit the ship's movement, which would generate

sloshing in the tanks.

The amplitude of sloshing depends on the condition of sea (wave pattern), the trim and the

speed of the ship.

No sloshing effect is implemented in the Simulator

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4.4 Loading

4.4.1 Preparations for Loading

It is assumed that all preparatory tests and trials have been carried out as per section 3.3 on

the ballast voyage prior to arrival at the loading terminal.

The loading of LNG cargo and simultaneous de-ballasting are carried out in a sequence to

satisfy the following:

1. The cargo tanks are filled at a uniform rate.

2. List and trim are controlled by the ballast tanks.

3. The cargo tanks are to be topped off at the fill heights given by the loading tables.

4. During topping off, the ship should have a trim limited to 1m by the stern, but if

possible kept on an even keel.

5. During the loading, the ship may be trimmed according to the terminal maximum

draught, in order to assist in emptying the ballast tanks.

6. The structural loading and stability, as determined by the loading computer, must

remain within safe limits.

An officer responsible for the operation must be present in the CCR when cargo is being

transferred. A deck watch is required for routine checking and/or any emergency

procedures that must be carried out on deck during the operation.

During the loading operations, communications must be maintained between the ship's

CCR and the terminal, and a telephone/agreed signals for the automatic actuation of the

Emergency Shutdown from or to the ship must be established.

At all times when the ship is in service with LNG and mainly during loading, the following

are required:

The pressurization system of the insulation spaces must be in operation with its automatic

pressure controls.

The secondary Level Indicating system should be maintained ready for operation.

The temperature recording system and alarms for the cargo tank barriers and double hull

structure should be in continuous operation.

The gas detection system and alarms must be in continuous operation.

Normally when loading cargo, vapour is returned to the terminal by means of the HD

compressors or shore compressor. The pressure in the ship's vapour header is maintained

by adjusting the compressor flow.

The cargo tanks must be maintained in communication with the vapour header on deck,

with the vapour valve on each tank dome open.

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The vent mast No.1 is maintained ready during the loading operation, for automatic

venting.

If the tanks have not been previously cooled down, LNG spraying is carried out.

Alongside of Terminal

a) Connect and bolt up the shore ground cable.

b) Connect and test the shore communication cable.

c) Test the telephone for normal communication with the terminal.

d) Test the back-up communication arrangements with the terminal.

e) Change over the blocking switch for the shut down signal from the terminal, from the

blocked to the terminal position.

f) Connect the terminal loading arms to the four LNG crossovers and one vapour

crossover. This operation is done by the terminal personnel.

g) Check that the coupling bolts or QCDC (Quick Connection and Disconnection) are

lubricated and have the correct torque.

h) In the cargo control room (CCR), switch on the cargo tank level alarms and level

shutdowns which are blocked at sea.

i) Switch the independent level alarms from blocked to normal on each tank.

j) Switch the derived level alarms from blocked to normal on each tank.

k) Verify that alarms for level shut downs blocked are cleared.

l) Connect the nitrogen purge hoses to the crossover connections and purge the air from

each loading arm, or using N2 gas from shore.

m) Pressurize each loading arm with full nitrogen pressure through the purge valve, and

soap test each coupling for tightness.

n) Bring the ship to a condition of no list and trim, and record the arrival conditions for

custody transfer documentation. Official representatives of both buyer and seller are

present when the printouts are run.

This list is in this manual mainly to give a clue as to what is happening when going

alongside the terminal. It is not possible to do all these operations on the simulator.

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4.4.2 Cargo Lines Cool Down

Assuming the ship has the port side alongside.

a) Open the following valves on the spray line: (V12055, V12053, V12752, V12751) -

MD121), and the Liquid isolation valves on the tanks:

CT 1 Liquid Isolation Vlv (V20110)-MD201




b) On each vapour dome, open the following valves to allow the supply of LNG to the

spray rings:

CT 1 (V20155, V20151, V20152) - MD201

CT 2 (V20255, V20251, V20252) - MD201

CT 3 (V20355, V20351, V20352) - MD201

CT 4 (V20455, V20451, V20452) - MD204

c) Open the vapour manifold valve(V12071)MD120 or MD121.

d) Open manifold valve on liquid manifold 3P (V12031) and liquid manifold cool down

valve (V12065), which will allow liquid into the stripping/spray main via crossover

valve (V12050) MD120 or MD121-, if necessary for additional cool down in the

tanks.

e) Assuming that the aft loading arm 4P is the first to be cooled down:

Crack open the CT1 & CT4 liquid filling valves (V20100 & V20400)-

MD 201 & MD 204.

f) Inform the terminal that the ship is ready to receive LNG.

Open the LNG quick closing valve(V12041)-MD 120 or MD 121 on the liquid

manifold.

The terminal should be instructed to begin pumping at a slow rate for approximately 15

minutes, in order to gradually cool down the terminal piping and the ship's headers.

g) Open valve 4P Liquid Double Shut of Vlv(V12043).

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Slowly increase the terminal pumping rate until the liquid main and spray headers have

cooled down (approximately 15 to 20 minutes).

Note

In order to avoid the possibility of pipe sections hogging, the liquid header and crossovers

must be cooled down and filled as quickly as possible.

h) Open the filling valves to the tanks;

CT 1 Liquid Filling Vlv (V20100) -MD201




fully on completion of the loading arm's cool down.

i) Open liquid manifold valves: (V12033, V12013, V12023) and the LNG manifold

quick closing valves (V12031, V12021and V12011)-MD120 or MD121

j) Inform the terminal to increase the loading rate to the ship's maximum capacity.

k) Close Liq. Manif Cool Down valve (V12065) - MD120 or MD121.

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On each tank keep open the stripping/spray valves to the spray rings in order to avoid over-

pressure due to line warm up.

l) Start one HD compressor and adjust the flow rate to maintain the tank vapour

pressure at 50 mbar/5 kPa.

4.4.3 To Load Cargo with Vapour Return to Shore

It is assumed for clarity of the description that all valves are closed prior to use and that the

ship is port side alongside.

Checks to be made before cargo operation:

a) Test the remote operation of all tank valves and manifold crossover valves.

b) Test the remote operation of ballast valves. Test the HD compressors, ballast pumps,

safety systems and glycol heating systems.

Safety precautions:

a) Ensure that the hull water curtain is in operation on the port side, if the ship loading

from portside.

b) Prepare the fire fighting equipment, water hoses and protective clothing for use. In

particular, the manifold dry powder monitors should be correctly aligned ready for

remote operation. Ensure the water spray system on deck is ready for operation,

filters installed and off shore blanks removed.

c) Prepare both HD compressors for use with seal gas and the lube oil system in

operation.

Nitrogen system:

a) Ensure that the nitrogen storage tank is at maximum pressure and that the two

nitrogen production plants are ready for use.

b) Arrange nitrogen piping to preferentially feed the primary insulation spaces.

c) Check the additional supply valve (V24023)-MD 240 as stand-by.

d) Adjust the set point of the nitrogen supply regulating valves(V24022) & (V24021) -

MD240 at 2 mbar/0,2 kPa.

e) Adjust the set point of the nitrogen exhaust pressure control valves,

primary insulation space (V24032 at 4 mbar/0,4 kPa

secondary insulation space( V24031 at 4 mbar/0,4 kPa.

f) Switch on the unblocking level alarms in the Custody Transfer. CTS should be open

before loading arm cool down operation.

g) Open gas outlet valves on tank gas domes (normally these valves are left open).

MD 201 – MD204

Tank No.l V20170

Tank No.2 V20270

Tank No.3 V20370

Tank No.4 V20470

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h) On HD gas compressors open valves(V31907, V31909, V31910 & V31912)-MD

319.

i) Check:

Optical fibre(shore) system, operates from Variable Page 11003

Connection of liquid and vapour arms

Communications with shore

Ship/shore electrical and pneumatic connection and safety devices

ESDS

j) Carry out safety inspections.

k) Complete the relevant ship/shore safety checklist.

l) Open filling valve of tank No.4 and tank No.1 fully, (V20400 and V20100)-

MD 204& MD 201.

Open filling valves of tank No.2: (V20200, & tank No.3:V20300)- MD 202 &

MD203

(See cargo line cool down)

m) Increase the loading rate.

n) Start the de-ballasting program. Keep draught, him and hull stresses within

permissible limits by controlling de-ballasting.

Refer to trim and stability data provided.

o) Start bulkhead heating in the cofferdams. This should already be running in

automatic.

p) Monitor tank pressures in order to achieve a pressure of about 80 mbar/8 kPa. Open

valve the Comp.Suct.Vlv (V30601)-MD300 and Vap.Ret Throttling Vlv(V31900)

(MD300) on the compressor's discharge side. Start one or both HD compressors as

necessary.

q) Adjust the opening of the tank filling valves to maintain an even distribution.

r) Ease in the filling valve of each tank as the tank approaches full capacity. Arrange to

terminate tanks at 15 minute intervals.

s) High level alarms. When any tank approaches 95% capacity inform the shore.

t) High/High level alarm. Standby valve before level approaches about 98% (signal

from main segment).

Close valve at correct filling limit capacity.

Very High level alarm will sound at 98.5% capacity and filling valve concerned will

automatically close (signal from independent sensor).

Extreme High level alarm will operate at 99% capacity and will initiate the

Emergency Shut Down System (signal from independent sensor).

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Warning

Extreme and very high level alarms and shut downs are emergency devices only, and

should on no account be used as part of the normal topping-off operation.

u) Before topping-off the first tank, request shore to reduce loading rate and continue

reducing when topping off each following tank. When a tank is at its required level,

close the corresponding loading valve tank No.1 V20100, tank No.2 V20200, and

tank No.3 V20300. It is convenient to finish loading by the use of tank No.4 for ease

of line draining. Leave a capacity of 50 m3 for this purpose.

v) Stop loading when the final tank reaches a capacity according to the filling chart,

minus an allowance for line draining and leave tank No.4 loading valve open

(V20400).

w) Liquid lines, including the horizontal part of the crossover, will automatically drain

to tank No.4. The inclined parts of the manifold are purged inboard with nitrogen.

x) On completion of draining loading arms, close the liquid manifold ESDS valves. The

shore lines are now pressurized at 2 to 3 bar with nitrogen.

y) Open the liquid manifold valves (V12011, V12021, V12031 and V12041)-MD 120

or MD 121 to allow the nitrogen to flush the liquid into No.4 tank. Close the valves

when the nitrogen pressure has fallen to 0 bar. Repeat the operation 3 times, or until

no liquid remains in the manifold lines. If there is a problem opening the valves due

to filling height in the tanks, go to variable page 54000 were the ESD system may be

shut off. Remember to turn it back on when the operation is finished!

z) The purging of the liquid lines should be carried out one at a time.

aa) When gas readings obtained from an explosimeter are less than 50% LEL at the vent

cocks, all valves are closed and the loading arms are ready to be disconnected.

bb) Leave loading valve of tank No.4 (V20400) open until the piping has returned to the

ambient temperature.

In CCR

a) Tank level alarms. Inhibit independent level alarms prior to proceeding to sea.

b) Complete the de-ballasting operation to obtain an even keel situation for final

measurement. When measurement is completed, adjust the ballast tank levels for

sailing condition.

c) Stop the HD compressors just prior to sailing, before closing vapour manifold ESDS

valve (V12071) MD120 or MD121 (Ship is loading from portside) for nitrogen

purging and disconnecting the loading arms. If departure is delayed, the vapour

return to shore should be continued. Close CTS by independent surveyor

d) Disconnect the vapour arms.

e) Prepare the cargo system for gas burning at sea.

f) Open valves necessary to allow warming up. These are normally the filling valves

and spray valves on the tank domes.

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4.4.4 De-Ballasting

Operating Procedures

It is assumed that the main sea water crossover pipe is already in use, supplying other sea

water systems, e.g. the main circulating system, the sea water service system and that the

cargo and ballast valve hydraulic system is also in service.

To De-Ballast the Ship By Gravity

Caution

Mal-operation of the ballast system will cause damage to the GRP pipe work. Damage is

generally caused by a pressure surge due to sudden changes in the flow rates. During the

de-ballasting operation this can be caused by the opening of a full or partly full tank into

the main lines when under vacuum.

Under no circumstances should a vacuum be drawn on closed ballast main. Before starting

deballasting operations, the main lines must be purged of any air pockets in the following

manner.

a) Open the overboard discharge crossover line valves (V40103 and V40104)- MD 401.

Open also the suction valves (V40111, V40112), filling & discharge valves(V40133,

and V40134). Open overboard discharge valve (V40110).

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b) Open the forward deep ballast tank valves port and starboard (V40011, V40021) –

MD 400, or No. l ballast tanks port and starboard (V40012, V40022), if the forward

ballast tanks do not have sufficient head of water to gravity flow .

A flow will now be established

c) Open the valves on the tank(s) to be emptied as per the deballasting plan.

Deep tank port V40011

Deep tank starboard V40021

Deep tank centre V40001

No. l port V40012

No. l starboard V40022

No.2 port V40013

No.2 Starboard V40023

No.3 port V40014

No.3 starboard V40024

No.4 port V40015


Engine room port V40016

Engine room stb'd V40026

After peak tank V40109 (if applied)

Fore peak tank V40000 (if applied)

When it becomes necessary to start the ballast pumps:

d) Close BW Suction Aft valves (V40112 and V40122) –MD 401.

e) Check that the ballast tank valves are open - MD 400

f) Start the ballast pump(s).

g) Open the pump(s) discharge valve (V40114 (N0.1)), (V40124 (N0.2)).

h) If you feel you need the third pump, start this one as well in the same manner.

i) As the tank reaches the required level, open the valves on the next tank before

closing the valves on the first tank.

j) When suction has been lost on all tanks, close the discharge valves on the pumps

(V40114 (N0.1), V40124 (N0.2)) and stop the pumps.

k) Close all tank valves, ballast crossover valves (V40103 and V40104), and the

overboard discharge valves V40110.

l) Strip the ballast tanks as required (see below).

To Strip the Ballast Tanks Using a Ballast Eductor

Using the GS pump and the ballast eductor

a) Open the eductor drive water overboard discharge valve (V40141)- MD401.

b) Open the drive water supply from the GS pump, valve (V40143)-MD401.

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c) Open the Low Suction Sea Chest Vlv(V40108).

d) Start the GS pump (R40105).

e) Open eductor suction valves (V40101 and V40102).

f) Open the valve on the tank to be stripped.

g) When one tank has been stripped, ensure the next tank valve is opened before closing

the previous tank.

h) When all tanks have been stripped, close the eductor suction valves( V40101 and

V40102).

i) Stop the GS pump (R40105).

j) Close the eductor drive water valve (V40143).

k) Close the eductor overboard discharge valve (V40141 and the Low Suction Sea

Chest V40108.)

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4.5 Loaded Voyage with Boil-Off Gas Burning

4.5.1 Normal Boil-Off Gas Burning

Introduction

During a sea passage when the cargo tanks contain LNG, the boil-off from the tanks is

burned in the ship's boilers. The operation is started on deck and controlled by the ship's

engineers in the CCR and Engine Control Room. If for any reason the boil-off cannot be

used for gas burning, or if the volume is too great for the boilers to handle, any excess

vapour is vented to atmosphere via No. l vent mast.

Operation The cargo tank boil-off gas enters the vapour header via the cargo tank vapour domes. It is

then directed to one of the LD compressors, which pump the gas to the boil-off/warm-up

heater. The heated gas is delivered to the boilers at a temperature of +35°C via the Fuel

Gas Master Vlv (V30610). The compressors speed and inlet guide vane position is

governed by fuel demand from the boiler(s) and cargo tank's pressure. The system is

designed to burn all boil-off gas normally produced by a full cargo, and to maintain the

cargo tank pressure (i.e. temperatures) at a predetermined level.

If the propulsion plant steam consumption is not sufficient to burn the required amount of

boil-off, the tank pressure will increase and eventually the steam dump will open, dumping

steam directly to the main condenser. The main dump is designed to dump sufficient steam

to allow the boiler to use all the boil-off produced, even when the ship is stopped.

The flow of gas through the LD compressors is controlled by adjusting the compressor's

speed and inlet guide vane position. This is directed by the boiler combustion control when

gas burning is initiated. The normal boil-off in the boiler combustion control has to be

selected as well as the maximum and minimum allowed tank pressures and the tank

pressure at which the main dump operates.

For normal operation the normal boil-off valve is selected at 60% boil-off provides 60% of

the fuel required to produce 90% of the boiler full steam capacity, and the minimum and

maximum tank pressures are selected at l050 and 1090 mbarA (105 – 109 KpaA).

If the normal boil off valve has been correctly adjusted, the tank pressures will remain

within the selected values. Should the selected normal boil off value be too large, the tank

pressure will slowly be reduced until it reaches the minimum value selected. If the tank

pressure value reduces to below the minimum value selected, the normal boil-off value will

be reduced until the tank pressure has increased again above the selected value.

If the selected normal boil-off value is too small, the tank pressure will slowly, increase

until it reaches the maximum value selected. If the tank pressure value increases above the

maximum selected value, the normal boil-off value will be increased until the tank pressure

reduces again below the selected value.

If the tank pressure continues to increase because the steam consumption is not sufficient

to burn all the required boil-off, the steam dump will open.

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The steam dump is designed to open when the normal boil-off valve is 5% above the

original selected value and when the tank pressure has reached the pre-selected dump

operating pressure.

With the present setting, an increase of 5% of the normal boil-off corresponds

approximately to an increase of tank pressure by 40 mbar above the maximum tank

pressure selected.

The cargo and gas burning piping system is arranged so that excess boil-off can be vented

should there be any inadvertent stopping of gas burning in the ship's boilers. The automatic

Vapour Header Vent control valve (V12771)–MD 330 at No.1 vent mast is set at 230

mbar to vent the excess vapour to atmosphere as tank protection system.

If the gas header pressure falls to less than 40 mbar above the primary insulation space

pressure, an alarm will sound.

In the event of automatic or manual shut down of the gas burning system (or if the tank

pressure falls to 5 mbar above the insulation space's the Fuel Gas Master Vlv V30610 will

close and the gas burning supply line to the engine room will be purged with nitrogen.


It is assumed that all valves are closed prior to use.

a) Prepare LD compressors No.1 and 2, the boil-off heaters and the engine room gas

burning plant for use.

b) Open Vapour Head Vent Shut Off Vlv (V12772)-MD 121 to No.1 Vent Mast.

c) Check that the following valves on the vapour domes are open and locked in

position:

CT No.1: Open and lock in position valve V20170 – MD201

CT No.2: Open and lock in position valve V20270 – MD202.



The valves should already be locked in the open position.

d) Open vapour supply to the LD compressors valves (V30601)- MD300 and gas

heaters via the mist separator (V30901,V30903, V30904, V30906)- MD309.

e) Open heater inlet and outlet valves (V30913 & V30914) –MD309, At No. 1 boil-

off/warm-up heater (L/D Heater)

.

Open steam supply Vlv (V30970) to the heater.

f) In MD330 there are quite a few controllers that work in series. First choose LADEN

or BALLAST on the “Tank Press Controller”. Set the LD Compressor Controller in

Cascade (meaning it will get its set point from the “Tank Press Controller”. The only

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place to set the flow now is on the controller in the engine room. Set the set point to

the desired consumption in the range of 0 to 10 t/h.

When the engine room is ready to start gas burning, ensure that there is sufficient nitrogen

to purge the lines to the boiler i.e. > 5 bar in the buffer tank.

g) Ensure that the gas outlet temperature of the heater is approximately 35°C. Open the

Fuel Gas Master Vlv (V30610) and start the LD compressor(s).

Note

If the volume of boil-off exceeds demand in the boilers, the steam dump should be put into

operation.

Should the system shut down for any reason, valve V30610(MD330) will close

automatically.

Trip causes:

Boiler manual trip ( ECR, and local ) : Not implemented

Both boiler trip : Not implemented

Gas content High-High at common vent hood : Not implemented

Fuel gas temperature Low-Low : Not implemented

ESDS activated : This Trip is implemented

Vent duct exhaust fan stop : Not implemented

Remote/manual close from local, CCR and ECR : Not implemented

Fire detection in ER : Not implemented

When stopping gas burning for any reason;

h) Stop the LD compressor(s), shut down the boil-off heater. Close the Fuel Gas Master

Vlv (V30610) gas supply to engine room and adjust the set point of vent mast

control (V12771) to l l00 mbarA.

4.5.2 Forced Boil-Off Gas Burning

Introduction

Consideration must be given to the economics of gas versus fuel oil burning before

undertaking forced boil-Off.

If, during a loaded passage, additional fuel gas from the cargo tanks is required to be

burned in the ship's boilers, it can be made available by forced vaporization using the

equipment on board.

The above operation, called Forced Boil-Off will be used to complement gas burning up to

100% of the boiler's fuel requirement.

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Operation

The normal gas burning arrangement is maintained and the forcing vaporizer is brought

into operation.

A single stripping/spray pump is used to pump LNG to the forcing vaporizer. The excess

flow from the pump is returned to the tank through the stripping header pressure control

valves (V20154, V20254, V20354, V20454).

Note

In normal operation the controlled return is directed back to the same tank where the

liquid is being drawn from.

After vaporization, the LNG vapour produced passes through the demister where the

possibility of liquid LNG carryover is eliminated. The vapour then combines with the

natural boil-off gas from the vapour header before being drawn into the suction of the LD

compressors.

One LD compressor is used for this operation.

The flow of gas through the compressors is controlled via the boiler combustion control

unit by adjusting the opening of the inlet guide vanes and motor speed.

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The split control is as follows:

Low load: Inlet guide vane control (-80 to +20 deg).

High load: Motor speed control (30-60Hz).

The boiler combustion control has to be switched to Forced Boil-off (FBO) mode, This

control is not implemented in the Simulator

The amount of forced boil-off to be produced is controlled by the throttling of the FCV to

the forcing vaporizer operated by the Boiler Combustion Control.

When changing over to 100% gas burning, the fuel oil flow through the FO rails is adjusted

to minimum. The FO supply to the burners will then be cut out and the FO system put on

recirculation. The FO combustion control loops are maintained energized to enable re-

lighting of FO burners in an emergency.

In the event of automatic or manual shut down of the gas burning system (or if the tank

pressure falls to 3 mbar above the insulation spaces pressure), valve Fuel Gas Master Vlv

(V30610) will close and the gas burning supply line to the engine room will be purged with

nitrogen. FO booster devices are incorporated in the control loop to allow a quick

changeover should the gas burning be tripped.


The cargo piping system is arranged for normal gas burning during loaded voyage.

It is assumed that all valves are closed prior to use.

a) Prepare the forcing vaporizer for use.

b) Open the stripping/spray header isolating valve for the tank/s to be used –MD121

If Using CT No.1: V12752, V12751, V12055

If Using CT No.2: V12752, V12751

If Using CT No.3: V12752

If Using CT No.4: V12053

If cargo tanks No.1 is used, open stripping/spray header isolating valve V12752, V12751,

V12055. If tank No.2 is used open stripping/spray header isolating valve V12752, V12751.

If No.3 tank is used open stripping/spray header isolating valve V12752. And if No.4 tank

is used open stripping/spray header isolating valve V12053.

c) Open stripping/spray header supply valve (V12054)-MD121 to the forcing vaporizer.

d) Open stripping pump discharge valves (V20150, V20250, V20350, V20450 and

stripping isolation valves V20155, V20255, V20355 and V20455). Start

stripping/spray pump and adjust the return flow to the tank through the stripping

header pressure control valves (V20154, V20254, V20354, V20454).

e) Run up the forcing vaporizer

f) Set the boiler combustion control on FBO mode, not implemented in the sim.

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g) Start No.1 LD compressor depending on gas demand.

h) Set control of liquid supply to the vaporizer and LD compressor control to auto

mode.

Cargo tank pressure control, 'Gas Management System'

Pressure range at ballast and laden voyage:

Ballast voyage: 47-67 mbar/4,7-6,7 kPa

Laden voyage: 1,050-1,080 mbarA/105-108 kPaA

Set point of safety valve and alarm point

Set point of safety valve: Pressure 25 mbar

Vacuum -10 mbar

Alarms:

Vent valve open 230 mbar/23 kPa

Vent valve close 210 mbar/21 kPa

High pressure alarm 200 mbar (For./LNG Vap. trip)

FO back-up order ON 30 mbar/3 kPa

Low pressure alarm 10 mbar/1 kPa

Low Low pressure alarm 3 mbar/0,3 kPa

Set point controller:

Set point of tank press. Control 70 mbar

Set point of tank protection control 50 mbar

Min. gas flow of F/V control 1,400 kg/h (20- 100%)

Set temperature of BOG temp. control 40°C

Preferred FGV position of LD comp. control 87%

Permissible range: 10-230 mbar

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4.6 Discharging with Gas Return from Shore Introduction

During a normal discharge, only the main cargo pumps will be used and a quantity of cargo

will be retained on board for cold maintenance of the cargo tanks.

The quantity to be retained is according to voyage duration of ballast passage.

If the ship has to warm-up tanks for technical reasons, the stripping/spray pumps will be

used to discharge the remaining cargo on completion of the bulk discharge with the main

cargo pumps.

During cargo discharge, LNG vapour is supplied from shore to maintain pressure in the

cargo tanks.

Operation

The main cargo pumps discharge LNG to the liquid header and then to shore via the mid-

ship liquid crossover manifold connections.

After an initial rise, the pressure in the tanks decreases. It then becomes necessary to

supply vapour from shore via the manifold and crossover to the vapour header into the

cargo tank gas domes in order to maintain a pressure of 1,090 mbarA/109 kPaA.

Should the vapour return supply from shore be insufficient to maintain tank pressures,

other means of supplying vapour to the tanks, either by using the tank sprayers or the LNG

vaporizer, have to be used.

The boil-off gas heater should be prepared and lined up for use in order to avoid venting

cold LNG vapour through No.1 vent mast.

Note All LNG terminals prohibit venting of flammable gas.

Ballasting is undertaken concurrently with discharging. The ballasting operation is

programmed to keep the vessel within the required limit of draught, trim, hull stress and

stability following indications obtained from the loading computer.

During the discharge period, the ship is kept on an even keel. If it is required to empty a

cargo tank, the ship is trimmed according to terminal maximum draught by the stern to

assist in stripping the tank.

Each tank is normally discharged down to a level of about 0.37 m. The quantity being

retained in the tanks varies according to the length of the ballast voyage, the expected

elapsed time before loading and the volume of boil-off that is estimated to be burned in the

ship's boilers.

One pump is stopped at a level of approximately 1.0 m to avoid excessive turbulence at the

tank bottom which creates disturbance at the suction of both pumps.

If the vessel is to warm up one or more tanks for technical reasons, the ship shall be

trimmed according to the terminal's maximum draught. The cargo remaining in the tanks to

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be warmed up will be discharged to shore or to other tanks using the stripping/spray pumps

on completion of bulk discharge.

The stripping pump is run together with the remaining main pump until the main pump

stops on low discharge cut-out.

On completion of discharge, the loading arms and pipelines are purged and drained to No.

4 cargo tank and the arms are then gas freed and disconnected. Due to the manifold

configuration, it is necessary to purge the cargo lines using nitrogen at a pressure of at least

3 bar. This is done several times to ensure successful draining at the manifold connections.

The vapour arm remains connected until just before sailing if a delay is expected.

4.6.1 Preparations for Unloading

It is assumed that all valves are closed prior to starting.

Preliminary preparation:

a) Checks to be made prior to starting cargo operations.

Test remote operation of all tank discharge valves and manifold

ESD valves.

Test remote operation of ballast valves.

Test operation of Emergency Shut Down Systems (ESDS).

b) Safety precautions:

Ensure that hull water curtain at mid-ship is in operation.

Prepare fire fighting equipment, water hoses and protective clothing for use.

c) Cargo tanks level arms:

Switch on high level alarms.

d) Tank vapour domes - confirm that:

Open and lock in position valve V20170 (Tank No.1)




These valves must be locked open at all times when the ship has cargo on board,

unless a tank is isolated and vented for any reason.

e) : Open Vapour crossover block valve (V12079) -MD120 or MD121.

f) Cargo pumps:

Check insulation resistance of electric motor and related cables prior to supplying

power to the cargo pumps. (This can not be done in the Simulator)

g) Check connections of liquid and vapour arms.

Check communications with shore.

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Check ship/shore link.

h) Purge the manifold connections with nitrogen to be supplied from shore when shore

is ready.

If shore agrees:

i) Open Vapour manifold ESD valve (V12071)-MD120 or MD121

j) Liquid connections:

Open manifold ESD valves (V12011, V12021, V12031, and V12041).

k) Test Emergency Shut down System (ESDS) from shore and from the ship as

required. Re-open liquid and vapour ESD valves.

When it is agreed with shore, then the cool down may commence.

4.6.2 Liquid Line and Arm Cool down before Discharging

To cool down the cargo discharge lines proceed as follows: assuming that No.3

stripping/spray pump is being used, all manifold lines and the ESD valves are open, having

been purged with nitrogen.

a) Open No.3 stripping/spray pump discharge valve(V20350) from to 30%.

b) Open the Spray Cross Over & Spray Header Iso valves (V12050, V12751, V12752),

the Liq. Manif. Cool D. Vlv’s(V12061, V12063, V12065, V12067) at the port

manifold.

c) Start the stripping/spray pump.

d) When hard-arms and shore side lines have cooled down to -100°C, open Spray

Header Iso Vlv(V12053), CT 4 Spray Isolation Vlv & CT 4 Spray By Pass

Vlv(V20455, V20456) & CT4 Liq Iso Vlv (V20410), Liq Manif Double Shut Off

Vlv’s( V12013, V12023, V12033and V12043). This will now cool down the ship's

liquid line.

The cooling down is complete when the manifold and ship's liquid line is

approximately - 130°C.

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e) Stop the stripping/spray pump.

Shut valves (V12053, V20455, V20456, V12061, V12063, V12065 and V12067)

Open valves (V20353 and V20354) to drain the line back to No.3 tank.

f) When spray line has warmed up, close valves (V12050, V12751, V20353 and

V20354)

On completion of cool down and when shore is ready for discharge, proceed with

unloading.

4.6.3 Discharging

Before starting the main cargo pumps for No.2 and 3 tanks (these being the first tanks from

which to commence discharge) it is necessary to fill the discharge column with LNG to

avoid a pressure surge in the lines. The spray pump for each tank is used for this operation.

When the discharge column is filled up, the vessel in ready to start discharge.

Inform the Engine Control Room that a main cargo pump is about to be started.

After preparation for start of cargo pump, sequence consol is to be operated. This is found

in MD 503. Make sure the CTS is turned on.

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a) Push start at the first pump (normally port) at the automatic sequence control.

b) The discharge valve will open to 12% and the loading valve will open to 100%, then

the pump will start and the sequence goes into AUTO mode.

c) Start the next pump in the same way with the automatic sequence.

d) After steady condition of the two cargo pumps start the automatic discharge sequence

controller. The liquid isolation valve will open fully, and the filling valve will close.

e) Adjust the set point of the two cargo pump controllers to increase the discharge flow.

Normal set point is around 450 A.

The preferred sequence of cargo pump starting, to obtain a stable discharge operation is as

follows: Tank No.3 → Tank No.2 →Tank No.4 → Tank No. 1.

f) Monitor the tank's pressure.

g) Request the vapour return from shore and continue to monitor the pressure to

confirm that it stabilises.

h) As the discharge pressure and flow rate increase, continue to monitor the pipe work

and loading arms for leakage.

i) Adjust the pump set points of the pumps to obtain optimum performance as indicated

by current, discharge pressure and pump graph.

j) It is important to maintain the tanks at a pressure of at least 100 mbar/10 kPa in order

to avoid cavitation and to have good suction at the pumps. If the tank's pressure falls

to 60 mbar/6 kPa request shore to increase the gas return.

If shore can no longer supply gas return, the LNG vaporizer will have to be started to

restore the tanks pressure.

k) Start ballasting operations. Keep draught, trim and hull stresses within permissible

limits by controlling the various ballast tank levels. Refer to trim and stability data

provided.

l) Continue to monitor the tank's pressure and the cargo pump's current and discharge

pressures.

Stop the main cargo pumps in each tank at approximately 1.1 m in tank No.4 and 0.3 m in

tanks No. l, 2 and 3. The above data is for reference only. Actual liquid level to be stopped

cargo pump shall be depended on selection of coolant storage tank and amount of required

heel for cooling down before along side of loading terminal.

Requirement of LNG for cooling down operation refer to Guidance Manual for reference.

Quantities of cargo remaining in the tanks after stripping refer to Guidance Manual for

reference.

Throttle in the main cargo pump discharge valve to 40% by adjusting the set point before

stopping the pump. If two main cargo pumps are in use in a tank, when the level reaches

1.1 m, throttle in the discharge valve on one pump to 40% and stop that pump. This is in

order to reduce turbulence around the pump suction.

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On completion of the final tank and after all cargo pumps have been stopped:

m) Drain the liquid line.

n) Stop the gas return from shore.

If stripping of tanks ashore is required use the forward manifold connection.

Purging and Draining of Loading Arms

When the shore terminal is ready to inject nitrogen and the pressure at the manifold is 2.5

bar.

a) Close the liquid ESDS manifold valves.

Purging is carried out one line at a time.

b) Open manifold Liq Manif 1P Vlv (V12011). If the ESD is active it will have to be

shut off at Variable page 54000. Remember to activate it again when finished.

c) Close the valve when the pressure on the manifold drops to 0 bar. Repeat the

operation twice. For the last operation, shut the bypass valve at approximately 1 bar,

in order to eliminate the risk of liquid back flow from ship's liquid line.

d) Repeat procedure b) to c) for each line.

Open the test drain valve on the loading arm(not implemented in the sim) to ensure that

there is no liquid present. When the required amount of methane (usually less than 1%) is

showing at the drain valve, close the shore terminal ESDS valves.

e) When purging is completed, proceed with the disconnection of the liquid arms.

f) Complete the ballasting operations for final measurement and for sailing condition.

Shortly before departure:

g) Vapour line connection:

Purge the vapour line with nitrogen from the shore terminal at a pressure of 2 bar.

Close the Vapour Manif Port Vlv(V12071), confirm that the gas content is less than

1% by volume at the drain valve.

After confirming that the gas content is less than 1% volume:

h) Disconnect the vapour arm.

i) Prepare the cargo system for gas burning at sea.

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4.6.4 Ballasting


It is assumed that the main sea water crossover pipe is already in use, supplying other sea

water systems, e.g. the main circulating system, sea water service system and that the cargo

and ballast valve hydraulic system is also in service.

To Ballast the Ship

Caution

Incorrect operation of the ballast system will cause damage to the GRP pipe work.

Damage is generally caused by a pressure surge due to sudden changes in the flow and the

presence of air pockets. During the ballasting operation great care must be taken to ensure

that flow rates are adjusted smoothly and progressively. In particular, the pumping rate

should be reduced to one pump when filling only one tank and make use of the discharge to

sea to further reduce the rate before shutting the final tank valve.

It is necessary to eliminate the air pockets that may be present in the piping before

proceeding with the normal ballasting operations. This is achieved by running ballast into

either of the Deep ballast or No.1 ballast tanks.

It is important not to compress any air in the system. To achieve this, the valve admitting

water to the system should be opened last.

Fill by Gravity

a) Open the WBDS Valves (V40021 and V40011)-MD 400 on the deep ballast tanks.

b) Check that the BW crossover valves (V40103 and V40104) –MD 301 are open.

c) Open the ballast Aft Suction Valves (V40122 and V40112).(suction aft for Pump 1 &

2)

d) Open the Sea Chest Valve (V 40108)

e) Open the Suction Forward valves f (V40111 and V40121). When a flow has been

established to the deep ballast tanks, the WBDS Valves (V40021 and V40011) can

be shut.

f) Open the valve(s) on the tank(s) to be filled as per the ballast plan.




No. l port V40012


No.2 port V40013


No.3 port V40014


No.4 port V40015

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g) As each tank reaches the required level, open the valve of the next tank before

closing the valve of the full tank.

h) When all the tanks are at their correct level, shut the tank valves, ballast main valves

and gravity filling valves (V40021, V40011, V40022 and V40012).

Note

The speed when filling by gravity will sharply decrease as the level of the water line is

approached. The tanks will require to be filled to their capacity with the ballast pump.

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To Ballast the Ship Using the NO.l Ballast Pump

a) Open the valve(s) on the tanks to be filled as required by the ballast plan.




No. l port V40012


No.2 port V40013


No.3 port V40014


No.4 port V40015






b) Open the sea water crossover valves (V40103 and V40104)-MD401

c) Open sea water suction valve to the No.1 pump (V40112).

d) Start the No. 1 ballast pump.

e) Open the pump discharge valve (V40113).

f) As each tank reaches the required level, open the valve of the next tank before

closing the valve of the tank which is full.

g) Close the final tank valve when the required level is reached.

h) Close the pump discharge valve (V40113) and stop the pump.

i) Close all other valves.

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To Ballast the Ship Using the N0.2 Ballast Pump

a) Follow operations a) to b) inclusive.

b) Open sea water suction valve (V40122) to the No. 2 ballast pump.

c) Start the pump.

d) Open pump discharge valve (V40123).

e) As each tank reaches the required level, open the valve of the next tank before

closing the valve of the tank which is full.

f) Close the pump discharge valve (V40123) and stop the pump.

g) Close all other valves.

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4.7 Pre-Dry Dock Operations

During the last loaded voyage before refit, a full inner hull inspection of all ballast tanks

and cofferdams must be carried out and a report sent to the Ship-owner company. This is a

Class requirement, to confirm the absence or presence of any cold spots. A Class surveyor

may attend the last discharge before refit, to inspect selected ballast tanks and cofferdam

spaces.

The ship will carry out a maximum discharge. The tank levels should be reduced to the

point where the main cargo pumps trip on low current. Then, using the stripping/spray

pumps, remove the last of the cargo until they also trip on low current. The ship will then

proceed to sea and commence the warm up, inerting and aerating, prior to arrival at the

refit yard.

4.7.1 Stripping and Line Draining

It is assumed that the cargo tanks have been discharged to their maximum with the main

cargo pumps which have been shut down. Discharge via the port side manifold.

Note Stripping/spray pump should be started at higher level than minimum start level (300 mm)

for the pump.

a) At manifold crossover:

Open valve 2P Liq Manif Cool Down Vlv(V12063)-MD120 or MD121

Close Liq Manif Shut Off Vlv’s (V12013, V12023, V12033, V12043) and 1P,3P &

4P Liq Manif ESD Vls (V12011, V12031, V12041)

b) Stripping/spray header:

Open Isolating Valves (V12053, V12751, V12751 and V12055)- MD 121.

Open stripping/spray header to liquid manifold crossover Vlv (V12050).

c) At required tanks:

Open stripping/spray discharge valves from individual tanks to give the required

performance, (V20150, V20250, V20350 and V20450).

Start stripping/spray pump(s).

On completion:

d) Stop final pump:

Close 2P Liq Manif Cool Down Vlv (V12063) and Liq Manif 2p ESD Vlv(V12021)

Open valves Spray Iso Vlv & Spray Return Vlv (V20454 and V20455)-MD204, to

drain down the header line to tank No.4.

e) When completed:

Leave open Spray header Iso. Valves (V12055, V12053, V12752 and V12751) in

order to warm up the line. When the line has warmed up, close the valves.

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Purging and Draining of Loading Arms

Purging is carried out one line at a time.

When the shore terminal is ready to inject nitrogen and the pressure at the manifold is 2.5

bar:

a) Open 1P manifold valve (V12011). If the ESD is active it will have to be shut of at

Variable page 54000. Remember to activate it again when finished.

b) Close the bypass valve when pressure on manifold drops to 0 bar.

Repeat the operation a further twice. On the last operation shut the bypass valve at

approximately 1 bar, in order to eliminate the risk of liquid back flow from ship's

liquid line.

Open the test drain valve on the loading arm to ensure that there is no liquid present. When

the required amount of methane (usually less than 1%) is showing at the drain valve, close

the shore terminal ESDS valves.

c) When purging is completed, proceed with the disconnection of the liquid arms.

d) Complete the ballasting operations for the final measurement and for the sailing

condition.

Shortly before departure:

e) Vapour line connection:

Purge the vapour line with nitrogen from the shore terminal at a pressure of 2 bar.

Close Vapour Manif. port ESD valve (V12071) and Vapour Cross over Block

Vlv(V12079)–MD 120 or MD 121.

Confirm that the gas content is less than 1% by volume at drain valve.

f) After confirming that the gas content is less than 1% volume:

Disconnect the vapour arm.

g) Prepare the cargo system for warming up the cargo tanks.

4.7.2 Tank Warm Up

Tank warm up is part of the gas freeing operations carried out prior to a dry docking or

when preparing tanks for inspection purposes.

The tanks are warmed up by recirculation heated LNG vapour. The vapour is recirculated

with the two HD compressors and heated with the cargo heaters to a preset value. (1st

stage: 0°C, 2nd stage: 75°C).

In a first step, hot vapour is introduced through the filling lines to the bottom of the tanks

to facilitate the evaporation of any liquid remaining in the tanks. In a second step, when the

temperatures have a tendency to stabilize, hot vapour is introduced through the vapour

piping at the top of the tanks.

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Excess vapour generated during the warm up operation is vented to atmosphere when at

sea, or returned to shore if in port. (The instructions that follow apply to the normal

situation, venting to atmosphere at sea).

The warm up operation continues until the temperature at the coldest point of the

secondary barrier of each tank reaches 5°C.

The warm up operation requires a period of time dependent on both the amount and the

composition of liquid remaining in the tanks and the temperature of the tanks and

insulation spaces. Generally, the warm up will require about 48 hours after vaporizing the

remaining liquid.

Initially, the tank temperatures will rise slowly as evaporation of the LNG proceeds,

accompanied by high vapour generation and venting. A venting rate of approximately

8,000 m3/h at 60% can be expected. On completion of evaporation, tank temperatures will

rise rapidly and the rate on venting will fall to between 1,000 and 2,000 m3/h at steadily

increasing temperatures.

Rolling and pitching of the vessel will assist evaporation. Temperature sensors at the aft

end of the tank give a good indication of the progress of warm-up. Slight listing of the

vessel will assist in correcting uneven warm-up in any one tank.

Gas burning should continue as long as possible, normally until all the liquid has

evaporated, venting ceased and tank pressures start to fall.

Preparation for Tank Warm up

a) Strip all possible LNG from all tanks.

b) When discharging the final cargo, remove the maximum LNG with the

stripping/spray pumps.

c) If discharge of LNG to shore is not possible, vaporize it in the LNG vaporizer and

vent the vapour to the atmosphere through the No.1 vent mast.

d) If venting to the atmosphere is not permitted, the vapour must be burned in the

boilers.

e) For maximum stripping, the ship should have zero list and should be trimmed down

at least 2.6 m by the stem.

f) Run the stripping pumps until trip by low current.

g) Remove the emergency pump that may have been placed in a cargo tank.

Operating Procedure

During the tank warm up, gas burning may be used by directing some vapour from the

heater outlet, to the boilers and by controlling manually this operation.

a) Install the spool piece Liquid Line/ Vapour Line (F12002) and open the

Vapour/Inertgas to Liqid Header Vlv (V12702) to discharge heated vapour to the

liquid header.

b) Prepare LD and HD gas heaters for use.

c) Adjust the temperature set point to between 20 and 25°C.

d) Prepare No.1 and 2 HD compressors for use.

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e) At vent mast No.1, open Vapour Header Vent Shut of valve (V12772)- MD121.

f) Manually adjust the pressure by use of the Vapour Header Vent Control Vlv

(V12771)- MD330 to 160 mbar/16 kPa.

g) Open the Compressor Suction valve (V30601)- MD 300, the compressor(s) suction

from the vapour header.

h) Open the compressor inlet and outlet valves (V31907, V31909, V31910 and

V31912)- MD 319.

i) Open the heater inlet and outlet valves (V31913, V31914, V31915, V31916)- MD

319, and the L/D, H/D Comp disch cross valve (V30920).

j) Open the vapour valves on each tank:





k) Open the filling valves on each tank:





l) Start both HD compressors and run the compressors in manual. Gradually increase

flow by the inlet guide vane position.

m) Monitor the tank pressure and adjust the compressor flow for maintaining the tank

pressure at about 160 mbar/16 kPa. It is possible to control tank pressure by (V12771

via valve V12772). Pressure build-up line may be used to exhaust excess vapour to

No. l vent mast through Pressure B. Up to Vent/Liq Conn Vlv (V12770). Liquid

main shall be normally used for warming up operation.

n) Check that the pressure in the insulation spaces, which have a tendency to increase,

remains inside the preset limits.

o) Monitor the temperatures in each tank and adjust the opening of the filling valve to

make uniform the temperature progression in all the tanks.

p) After twenty/twenty-four hours, the temperature progression slows down.

Eventually, the procedure of the second method described below, may be more

efficient.

q) Purge the emergency pump column with N2 to remove liquid in the column.

r) At the end of the operation, when the coldest temperature of the secondary barrier is

at least +5°C, or before switching to the second step, stop and shut down gas burning

system if used. Stop both HD compressors, shut the filling valves on all tanks and

restore the normal venting from the vapour header.

s) As alternative operation, the target temperature in the cargo tank is at least +5°C

when inerting with hot inert gas is applied. In this case total operating time for

warming up and inerting has taken approximately 58 hours.

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4.7.3 Inerting

After the tanks have been warmed up, the LNG vapour is displaced with inert gas.

Inert gas from the inert gas plant is introduced at the bottom of the tanks through the LNG

filling piping. Gas from the tanks is vented from the top of the tank through the vapour

header to the vent mast No.1, or to shore if in port. (The instructions which follow apply to

the normal situation, venting to the atmosphere at sea.)

Inerting is necessary to prevent the possibility of having an air/LNG vapour mixture in the

flammable range. The operation is continued until the hydrocarbon content is reduced to

less than 1.5%. The operation requires about 20 hours.

In addition to the cargo tanks, all pipe work and fittings must be gas freed. This is best

done with inert gas or nitrogen, while the plant is in operation for gas freeing the tanks.

Operating Procedure

a) Prepare the inert gas plant for use in the inert gas mode.

b) Open the vapour on each tank





c) At vent mast No.1 open valve (V12772)-MD121 and adjust the set point to 2.0 bar.

d) Install the Hold Gas Free/ liquid Line spool pieces( F12001)-MD121 connecting the

IG line to the LNG liquid header. Open the Vapour/ Inert Gas to Liq Head valve

(V12702).

e) Open the filling valves each tank





f) Start the inert gas generator and run it until the oxygen content and dew point are

acceptable.

g) On the dry air/inert gas discharge line, open the IG Main line Supply valve(V35042)

-MD350, supplying inert gas to deck.

h) Monitor tank pressures and adjust the opening of the fill valves to maintain a uniform

pressure in all the tanks. Ensure that the tank pressures are always higher than the

insulation space pressures by at least 10 mbar/1 kPa, but that the tank pressures do

not exceed 180 mbar/18 kPa above atmospheric pressure. In any case, during gas

freeing the pressure in the tanks must be kept low, to maximize the piston effect.

i) Approximately once an hour, take samples of the discharge from the vapour dome at

the top of each tank and test for hydrocarbon content. Also verify that the oxygen

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content of the inert gas remains below 1%. by testing at a purge valve at the filling

line of one of the tanks being inerted.

j) Purge for 5 minutes all the unused sections of pipelines, machines, equipment and

instrumentation lines.

k) When the hydrocarbon content sampled from a tank outlet falls below 1.5%, isolate

and shut off the tank. On completion of tank and pipeline inerting, stop the inert gas

supply and shut down the inert gas plant. Reset the valve system for aerating.

l) If the tanks remain inerted without aerating, shut Vapour Head Vent Shut Off valve

(V12772), raise the pressure to 100 mbar/10 kpa, then shut off the tanks.

Warning

If any piping or components are to be opened, the inert gas or nitrogen must first be

flushed out with dry air. Take precautions to avoid concentrations of inert gas or nitrogen

in confined spaces which could be hazardous to personnel.

4.7.4 Aeration

Introduction

Prior to entry into the cargo tanks the inert gas must be replaced with air.

With the Inert Gas and Dry-Air System in Dry-Air production mode, the cargo tanks are

purged with dry air until a reading of 20% oxygen by volume is reached.

Operation

The Inert Gas and Dry-Air System produces dry air with a dew point of -45°C.

The dry-air enters the cargo tanks via the vapour header, to the individual vapour domes.

The inert gas/dry-air mixture is exhausted from the bottom of the tanks to the atmosphere

at No.1 vent mast via the tank filling pipes, the liquid header, and spool piece and Vapour

Line/ Liquid Line valve (V12000). During aerating, the pressure in the tanks must be kept

low to maximize a piston effect.

The operation is complete when all the tanks have a 20% oxygen value and a methane

content of less than 0.2% by volume (or whatever is required by the relevant authorities)

and a dew point below -40°C.

Before entry, test for traces of noxious gases (carbon dioxide less than 0.5% by volume,

and carbon monoxide less than 50ppm) which may have been constituents of the inert gas.

In addition, take appropriate precautions as given in the Tanker Safely Guide and other

relevant publications.

The pressure in the tanks is adjusted to 120 mbar/12 kPa.

Aeration carried out at sea as a continuation of gas freeing will take approximately 20

hours.

Warning

Take precautions to avoid concentrations of inert gas or nitrogen in confined spaces,

which could be hazardous to personnel. Before entering any such areas, test for sufficient

oxygen > 20% and for traces of noxious gases; CO2 < 0,5% and CO < 50 ppm.

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Operating Procedure

a) Prepare the inert gas plant for use in the dry-air mode.

b) Install the Vapour Line/Liquid Line spool piece ( F12000) for venting the mixture of

inert gas/dry-air from the liquid header. Adjust the Vapour Header Vent Ctrl Vlv

(V12771) at a pressure of 160 mbar/16 kPa above atmospheric pressure.

c) Open the filling valves on each tank





d) Open the vapour valves on each tank.





e) Fit the spool piece Hold Gas Free/Liquid Line (F12001) and Liquid Line/Vapour

Line (F12002), and open the IG Main Line Ssupply Vlv( V35042) on the dry-

air/inert gas discharge line on MD350.

f) Start the dry air generator.

g) Open the valves (V12702)-MD121, V30601 and V30603 (MD300) to supply dry air

to the vapour header.

h) Observe the tank pressures and insulation space pressures, to ensure that the tank

pressures are higher than the space pressures by 10 mbar at all times.

i) Approximately once an hour, take samples from the filling pipe test connections to

test the discharge from the bottom of the tanks for oxygen content.

j) When the oxygen content reaches 20%, isolate and shut in the tank.

k) When all the tanks are completed and all piping has been aired out, raise the pressure

to 100 mbar in each tank and shut the filling and vapour valves on each tank. Restore

the tank pressure controls and valves to vent from the vapour header.

l) During the time that dry air from the inert gas plant is supplied to the tanks, use the

dry air to flush out inert gas from vaporizers, compressors, gas heaters, crossovers,

pump risers and emergency pump wells. Piping containing significant amounts of

inert gas should be flushed out. Smaller piping may be left filled with inert gas or

nitrogen.

m) During the time a tank is opened for inspection, dry air will be permanently blown

through the vapour header line in order to prevent the entry of humidity from the

ambient air.

n) The insulation spaces are to be maintained in a vacuum condition during cargo tank

maintenance.

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4.7.5 Limiting Factors

Temperature It is vital that the tank temperatures are kept as close as possible to the temperature of the

cargo since this will hamper the loading and/or discharging time.

Berth Time

Some terminals limit berth time. In order to fully outturn cargo it may be necessary to

reduce ballasting time by taking on reduced ballast alongside and ballasting in river

passage, or ballasting during discharge.

Stress The vessel must not exceed maximum stress limits (harbour condition) at any time during

cargo operations.

The vessel may also have operating constraints such as: leaking pipelines, failing valves,

inoperative pumps. These difficulties may be overcome during the discharging by a

carefully planned operation which compensates for them.

4.7.6 Discharge Plans

These plans are to be prepared prior to the vessel's arrival and should include instructions

on:

- Cargo stowage and quantity.

- Discharge rate.

- Permissible pump pressure.

- Approximate discharge time.

- Ventilation method.

- Emptying of loading arms and lines.

- Ballasting.

- Method of how to stop cargo pumps and to raise alarm in case of fire or pollution.

Copy of the discharge plan should be given to Terminal representative.

4.7.7 Cargo Handling Training from the Graphic Desk-top

Cargo handling training with the CHS LNG-M can be performed from the graphic desk-top

by means of mimic pictures or from the cargo consoles by means of the cargo operation

panels. All operations are similar in both versions, the only difference is the presentation

method to the trainee.

In the case of the graphic desk-top presentation it is essential to have the correct mimic

diagram available. The directory pages have to be used for such.

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4.7.8 Picture Directory General

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4.7.9 Picture Directory LM

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Layout

As the LNG-M is equipped with two pumps in each tank, there is no central cargo pump

room. From the manifold all cargo and vapour is distributed to/from the tanks via the

network of cargo/vapour deck lines and cargo/vapour crossover lines.

Commands controlled by the use of the mouse buttons:

- Start/Stop Pumps

- Open/Close Valves.

Trim

The trim is changed by changing the load moments of the fore and aft halves of the ship.

NOTE: This change may cause another load distribution which results in

different distribution of shear forces, bending moments and hull deflection.

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Heel (list)

The heel (list) is changed by changing the load moments to/from the side ballast tanks.

Manifold

Only the pressure at the manifold connections can be monitored just as you would onboard

a real ship.

These figures will give information about the functioning of the pumps, leaking

connections etc.

The flow will be possible to monitor at the different tank pictures.

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4.7.10 Pump Flow

The pump flow is generated by starting the pump and opening the discharge valve(s). This

ship requires that the cargo pump system is started and controlled by a sequence controller.

The flow rate will depend on:

- The pump speed

- The flow resistance caused by pipe characteristics

- Valve characteristics and valve settings

- The suction head (cavitation)

- The liquid density

- Tank pressure

Open/Close The discharge valve setting is controlled by means of clicking on the screen at the

individual tank picture.

The pump flow and the pump pressure are controlled by the PID controller.

Cavitation

If the suction head is too low, the pump will start cavitation. The critical suction head for

cavitation will depend on the vaporizing pressure of the liquid to be pumped and the

current NPSH (Net Positive Suction Head) of the pump. Cavitation will occur on the cargo

pumps, but not on the ballast pump.

Stopping

The pump is stopped by Automatic Sequence controller. Depending on stop mode, the

pump will be stopped by the controller, or will have to be stopped manually. After the

electric supply is stopped, the pump is brought to a complete stop after a while.

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4.7.11 Ballasting

The LNG-M is fitted with a double bottom in which ballast tanks are located.

These tanks are interconnected by means of a separate set of ballast water lines.

The ballast water pumps (3) are located in the ballast pump room (picture MD 401).

Ballasting is a process where sea water is loaded into segregated ballast tanks to ensure

proper immersion and to provide good manoeuvring and stability characteristics. In order

to lessen hull immersion and thus reduce fuel consumption, minimum quantities of ballast

should be taken. However, the quantity must be sufficient to submerge the propeller,

maintain vessel manoeuvrability, to avoid excessive vibration, to operate within approved

stress limits and to retain sufficient bow immersion.

Ballast should be evenly distributed to minimize stress. Tanks should be either empty or

full. Partially full or slack tanks should be avoided.

Start-up The appropriate ballast tanks are chosen and the ballast tank valves are opened by clicking

on the symbols.

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Sounding During the ballast operation the tank soundings can be monitored on the level indicator.

The total content can be viewed on the Bunker/consumables picture (MD 103).

Heel/Trim Furthermore the changes in heel and trim of the vessel will be shown on the indicators on

the same mimic picture.

Pumps The pump room can be viewed by clicking on the symbol for the ballast pump room (MD

401).

Starting Procedure The pumps can be started/stopped by use of the left/right mouse buttons.

The following is normal start procedure for centrifugal type pumps:

- Close the discharging valve.

- Open the suction valve.

- Fill the pump with liquid.

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- Start the pump.

- Open the discharging valve.

Segregated Ballast

The Segregated Ballast Tanks (SBT) is completely separate from the cargo and fuel system

and is permanently allocated to the carriage of ballast water only. SBT require separate

pumps and pipes dedicated to handling ballast water only.

Segregated ballast may be retained on board in order to restrict the air draught if it is

necessary because of weather conditions or restrictions of loading arms or shore gangway.

However, care must be taken not to exceed the maximum draught for the Terminal or for

hull stress.

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4.7.12 Inert Gas System

From the Inert Generator and distribution pictures the operator can carry out and control

the following operations:

- Operation of inert gas generator.

- Inerting of cargo tanks.

- Ventilation (gas freeing) of cargo tanks

Start-up Procedures The Inert generator is ready for operation as long as the burner is on.

1. Ensure that the oxygen analyzer and Inert Gas pressure indicator are working.

2. Open valves and start scrubber pump.

3. Start the blowers and open inlet valves.

4. Start burner by pushing "on" after opening fuel supply.

5. Open Inert Gas main valve on deck.

6. The Inert Gas-plant is now ready to deliver gas to the cargo tanks or the cargo

holds.

Shutdown Procedures 1. Close the Inert Gas main valve on deck.

2. Shut down the burner.

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3. Close the blower discharge valves and stop blowers.

4. Keep full water supply on the scrubber for a minimum of 1 hour.

Inerting/Venting The operator can choose inerting or air venting by either starting the burner or leaving the

burner off.

NOTE: Before commencing ventilation by fresh air, the tanks must be measured

for hydro carbon gas concentration. If the readings indicate gas

concentration above 2 % by volume, the tanks are to be purged with Inert

Gas until the hydrocarbon gas concentration has decreased to less than 2

% by volume. This will ensure that the atmosphere is kept below the

lower explosion limit throughout the ventilation process.

Inert Press/Flow The current Main Line Inert Gas Pressure and Flow can be read from separate indicators on

the Inert Gas plant picture.

Distribution

From the Inert Gas plant there is a network of deck lines to all tanks and holds for the

distribution of Inert Gas.

Tank Pressure

The tank pressure is indicated at each tank and should be closely watched in order to avoid

over-pressure or under-pressure when discharging or loading cargo.

It can also happen that due to temperature change of the cargo a pressure difference is

created which will have to be compensated by either the spray system or the H/D

compressor(s).

Pressure

During cargo operations the tank pressures are shown in order to monitor the variations.

Vapour return lines are connected to shore at the manifold so as to take away excess

vapour.

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4.8 Stress and Stability Calculations

For the purpose of calculating permissible stresses and stability the Cargo Handling

Simulator both in full-mission as well as desk-top version is equipped with both an

"online" and an "offline" LoadMaster load computer.

4.8.1 Online Calculations

During simulation the online LoadMaster load computer will constantly calculate and show

in the respective mimic pictures the results that occur from loading, discharging, ballasting

or any other changes in the vessels weight distribution.

The relevant mimic diagrams are given in the picture directory nos.:

104 Shear Forces

105 Bending Moment

106 Deflection

107 Stability

These can be called up in the normal way, but not be influenced during the running of the

simulation. Actual weights, volumes and levels can be read in the mimic diagrams:

101 Cargo Tank Overview

102 Ballast Tank Overview

103 Bunker/Consumables

Care should be taken when running simulation in fast speed. As the amount of calculations

for the stress and stability are numerous there can be a back lag in the updating of the

pictures in the mimic diagrams. This holds the danger of temporary inaccurate values being

represented in the various graphs thus resulting in wrong conclusions being drawn.

After resuming normal speed simulation again the correct graphical representations will

appear again on the mimic diagram displays.

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4.8.2 Offline Calculations

In order to perform preloading/discharging calculations as is common practice to ensure no

critical limit values are exceeded during the loading or discharging operations the system is

equipped with an offline LoadMaster load computer.

This feature is represented by the mimic diagrams nos.

601 LM Cargo Tank Overview

602 LM Ballast Tank Overview

603 LM Bunker/Consumables

604 LM Shear Forces

605 LM Bending Moment

606 LM Deflection

607 LM Stability

Once the cargo loading or discharging plan has been drawn up and the tank sequence

chosen, the values can be entered in the cargo bar graph and tank diagrams. As this can be

done step by step and tank by tank it is possible to monitor and check the values of shear

force and bending moment against the allowable limits indicated in the respective screens.

The input of the values for cargo should be done on the mimic diagram of the cargo

bargraph. Underneath each tank a changeable value for "% full" is given. A value entered

here will result in an indicative bar in the tank.

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Switching then to the shear force and bending moment graphs will show the actual status

blue curve. This status curve can then be compared with the yellow harbour condition and

the red open sea condition curves.

If at any stage the yellow curve should be exceeded and the simulator is in harbour

condition an alarm will sound and a flashing indicator will appear at the bulkhead

concerned. The same will happen if the simulator is in sea condition for exceeding of the

red curve.

Damage Stability

To check the vessels damage stability it is possible to simulate how the stability will

become if you get water ingress into the engine room or into hold spaces. This can be seen

at the off line load calculator.

In the Variable page Directory you can find a line called “Damage Stability”.

From here you can choose which compartment there is damage to. If the damage is in the

engine room, you can set the amount of water inside.

If the damage is in the ballast tanks the water level in the damaged tank will be decided

by the actual loading condition you have in the Load Calculator

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5. APPENDIX A The following pages will describe operation of the mouse and the keyboard, the old

Instructor-, the Alarm- and the Operator sections which is included in the simulator.

This can be used if the simulator is running without the Neptune Instructor System

5.1 Instructor Station

The instructor station includes the following equipment:

- Computer

- Hard disk

- Monitor

- Mouse and keyboard

- Printer

The instructor has full access to the model.

5.2 Student Workstation

The student workstation includes the following equipment:

- Computer

- Monitor

- Mouse and keyboard

- Printer (depending on configuration)

The student station has instructor controlled limitations to the model.

5.3 Printer

The printer is used as an alarm and event log.

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5.4 The Functions of the Major Facilities

5.4.1 Computer System

The instructor workstation manages the software and use of peripherals, simulation

components and, allows real time simulations and recording, as well as exercise replay.

The real time simulation functions will provide the following:

- Operation of workstations.

- Operation of instructor station.

- Recording of:

- Simulation data

- Student action data

The simulating software is written in C language running under the WINDOWS operating

system.

The instructor workstation and the other simulator and computing units will be linked

using Ethernet, which is a Local Area Network (LAN). This LAN enables the computers to

share the disk systems using the Network File System (NFS) and a computing task may be

routed to any computer having spare capacity. Future extensions will easily be integrated

into the existing system because of the standardised LAN communication.

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5.4.2 Instructor Workstation

The instructor workstation and the student workstations are connected together in Ethernet

and are exactly of the same type. All workstations have a standard mouse and keyboard

with dedicated instructor function-keys.

The instructor workstation will be the host computer and act as a server for all other

computers. The instructor functions are divided in two groups, the primary- and the

secondary functions.

The primary functions are:

- Start of simulator

- Stop simulator

- Select scenario

- Run simulator

- Freeze simulator

The secondary functions are:

- Change scenario

- Alphanumeric pages of variables

- Alphanumeric pages of malfunctions

- Alphanumeric pages of alarms

- Operating conditions

- Snapshots

- Replay

- Simulation speed (relative real time)

- Sound control

- Inhibit control of alarm systems

- Access control of input

The instructor has full control of the simulator and the training session through the above

listed functions. He can whenever he likes, change the environment during a scenario, and

evaluate the operators handling of the situation.

The log printer acts as:

- Event log

- Alarm log

- Malfunction log

The instructor can select each of these logs. If more than one is selected, all the requested

events are printed out in chronological order. These logs are also available

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5.4.3 Student Workstation

The student workstation is provided as the central training device. The following

familiarisation, procedural training and experience will be possible:

- Familiarisation with piping and equipment layout

- Studies of process optimising and fuel economy

- Separately studies and tuning of control loops; temperature, level and pressure

- Familiarisation with the load calculator

- Preparation for port arrival/ departure

- Preparation dock set/ departure

- Preparation for loading and discharging

- Preparation for sea voyage

During each of these conditions, a number of systems must be tuned to function properly.

Economic and safe operation of the ship is based on reliable equipment and skilled officers

who can take correct decisions at the right time. These simulations are partly made possible

by a well developed man-machine interface.

The system design facilities in the KONGSBERG MARITIME CARGO HANDLING

SIMULATOR concept, has taken all these factors into consideration during design and

engineering. The result is a comprehensive system that allows the students to work under

conditions close to real ship environment.

The student workstation may be run in the full simulation or part task simulation mode:

- In full simulation mode the workstation reflects the behaviour of the total current

simulator scenario for the student to observe and to influence or change.

- When operated in part task mode the student has full control of the simulation

program and scenario he has selected to run, completely independent of the simulator

itself.

5.4.4 Printer

The printer acts as:

- Event log

- Alarm log

- Malfunction log (only accessible by instructor)

Each of these logs can be selected by the student/instructor. If more than one is selected, all

the requested events are printed in chronological order.

5.4.5 Mouse

Connected to the Desktop station is a standard mouse. The mouse moves the cursor on the

screen.

Function of left button is: START pump/compressor or open valve.

It will also utilise operation of buttons in the model drawings, retrieval of new sub systems

or call display windows.

The push button on the right hand side, is used for execution of commands to STOP

pumps/compressors, CLOSE valves or reset of malfunctions introduced.

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5.4.6 Keyboard

The keyboard is used to:

- change set point of controllers

- call new model drawings

- change variables in the variable list

- change intensity of malfunctions

- type text strings in connection with creation of scenarios and initial conditions

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5.5 Operation

5.5.1 Function buttons & blue pages

The functions are only accessible when in Instructor mode (all except the RUNNING,

FREEZE, STOP and SCENARIO which can be selected from Operator Mode).

Keyboard Key Function

F1 Run simulation

F2 Freeze simulation

F3 Stop the simulator

F4 Make Snapshot

F4+shift Snapshot Directory

F5 Operating Condition

F6 Scenario

F6+shift Init Condition

F7 Recall Picture

F7+shift Mark Picture

F8 Alarm Log Summary Display

F8+shift Page Acknowledge

F9 Malfunction List

F10 Variable List

F11 Alarm List

F12 Alarm Silence

F12+Alt Toggle window decorations

Home Directory

Home+shift Select Picture

Page Up Previous picture

Page Down Next picture

Ctrl + P Print hardcopy to default printer

Ctrl + L Display Message Log

This list may vary dependent of type of Desktop/Operating system and age of installation.

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5.5.1.1 Scenario (F6)

A scenario is a predefined list of actions and or malfunctions that will take place during the

simulation when Running is activated. Almost any action and malfunction available in the

simulator can be included in a scenario. The scenario push button, when activated, displays

a directory of the scenarios already created. This feature allows the instructor to load an

already existing scenario or creating a new one.

To create a scenario, enter scenario by pressing SCENARIO button. Prompts on the screen

will guide you through the preparation required. Point and click the software button

CREATE at the lower part of the screen, and then point and click at the position where to

locate the new scenario (S01 to S20).

After prompt and having typed the name of the scenario, press ENTER. A prompt will then

ask for an INITIAL condition which will be the basis for the scenario. Type in the

appropriate initial condition (101 to 160) and press enter. If accepted, prompt line will add

initial condition name and colour changes.

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5.5.1.2 Initial Condition Directory (Shift+F6)

An Initial Condition is a specific condition of the total simulation plant, comprising a

complete set of data and variables. When activating the Init Condition push button, a list of

all created initial conditions appears.

To store an initial condition to later use, the following procedure must be carried out.

Press Freeze. Choose display INIT CONDITION and click on software button CREATE.

Type in name of the exercise to be saved in one of the vacant locations and press enter.

During the process of creating the exercise its name starts flashing. After few seconds, the

new initial condition is made, and the simulation can proceed by pressing Running.

To load an Init Condition, press Freeze and click with left mouse button, on the Init

Condition selected. Loading is completed when the name of the exercise turns steady.

From this step the simulation can start on condition that Running is pressed.

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5.5.1.3 Operating Condition (F5)

This function allows the instructor to vary the external parameters, the ship dynamics as

well as internal processes. In addition the instructor can introduce fixed values of selected

variables.

By pressing this button, an Instructor picture called Operating Condition is displayed. This

picture is divided into several groups where the following parameter can be altered.

Access: Different access levels can be set.

Sound Control: Allows the Instructor to control the volume of the Sound System in the

Cargo control room where the full-mission simulator is installed if applicable.

Fixed process: Instructor can introduce fixed process values for some of the major

parameters in the systems. Independent of consumption, the fixed values will remain the

same. The fixed process is valid for the following systems:

Boiler isolation sets the steam pressure to cargo pumps at 15 bar.

Inert gas fixed sets the flue gas oxygen content to 3,5 %

Inhibit: The demand for realism with regard to what kind of alarm indication to be most

appropriate, depends on the training situation and the number of students present. The

functions are disabled when pressed. For the maximum version, the following functions are

available.

Alarm Horn (and alarm lamp), operational only.

Keyboard Buzzer.

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Log printer 1: Determines which events or alarms to be logged on the printer. If required,

all buttons can be activated. Press the appropriate push button(s) to satisfy the exercise to

be run. The actual event/ alarm is printed together with the time it took place.

The choice is as follows:

Alarm: In general all alarms that occur are printed.

Event: All actions from the student are printed, like start/stop of pumps, opening or

closing valves.

DataChief: All actions from the Electrical Power Plant will be printed. (If connected)

Malfunction: Setting and Resetting of Malfunctions.

Instructor: Not in use

-Log printer 2: For future use.

-Log printer 3: For future use.

Snapshot: A snapshot represents the condition of the simulation at the time it was created.

If the student fails to run the simulation properly and for instance this results in a black out

or any other abnormal condition, the situation can be corrected by simply retrieve a

snapshot prior to the "accident". Each Snapshot is identified by the time it was created,

manually or automatically. When generated automatically, the interval between each

snapshot has to be specified. See also description of Snapshot push button.

5.5.1.4 Malfunction Editor

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Gives ability for editing and creating of malfunctions prior to start or during the simulation.

It is a prerequisite that a scenario is loaded into the desktop. To create a malfunction, click

on software button CREATE and click at one of the buttons M01 to M40 and type in a

descriptive name of the malfunction.

IMPORTANT: When a malfunction name has been typed and ENTERED, a prompt

will ask you which TAG name from the Malfunction List is wanted.

This tag name must be written with full style name and number directly copied from

Malfunction List. In addition, type in _S. Otherwise tag will not enter. When prompt

changes colour, it will be written ex.. M1301_S, and you are allowed to continue.

In the section VALUE

The active and passive values are entered. When prompted, type in values either

digital (0,1,2 etc.) or analogue in percentage of max. value.

In the section ACTIVE

The value entered is the new default as the fault is activated. Selection of how the

malfunction will be introduced; continuo’s fault or repeating fault in the section

“AUTOMATIC MODE”.

In the section PASSIVE

The value entered is starting level at the time when the malfunction is activated.

UNIT

Engineering unit or percentage. Not necessary to be entered.

Under column AUTOMATIC MODE:

Activating this will make fault go active, and stay active, when

entered time is reached.

Activating this button will make fault go active, and then off

again when time limits entered are reached.

Activated, this button will make fault go on and off repeatedly within

specified time limits, as long as scenario is run.

When activated, time ramp for fault to develop can be specified.

Common for all four function buttons are that faults can be simulated after entering a

scenario only when buttons are activated. When active, buttons change colour. Ramp

function can be active together with any of three other buttons.

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


Actions to be created in the same way as malfunction editor. Input of tag names similar to

malfunctions editor, adding underscore S after the Malfunction tag.

When starting a scenario, malfunctions and actions which are activated during the

simulation, must be chosen by clicking on software buttons. Changing colours will indicate

which buttons are activated. In front of each button there is a light with 2 circles.

Outer circle lit means action is activated, but waiting for set time interval to be reached in

order to switch action on.

Inner circle lit means that READING is active, meaning set intervals are reached, and

action started. On the bottom half of screen (buttons A41 to A80) is event malfunctions.

Used and created as malfunction, but triggering actions instead of malfunctions. Such as

closing of valves.

5.5.1.5 Sound

Toggles sound system on/off. Valid for operational simulator only.

5.5.1.6 Time Editor

Allows altering the time for which the malfunctions or actions to take place.

Clicking on CHANGE TIMEPHASE software button enters a line on time section of

picture. Use the inner scroll buttons to increase or decrease the time between actions or

events to take place. Outer scroll buttons to changes time phase.

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


5.5.1.7 Event Editor

Used to supervise and allows adjusting events and event conditions.

5.5.1.8 Snapshot (F4)

Takes a snapshot of simulation for later reference. Places snapshot in snapshot directory is

referred to by time.

NOTE! As soon a new Initial Condition is loaded, all snapshots are deleted. However, a

snapshot can be stored as an Init Condition (has to be done before loading a new initial

condition).

Kongsberg Maritime

Doc.no.: SO-1295-D / 7-Jan-11


5.5.1.9 Evaluation Editor

For evaluation of the student throughout the exercise taking place. Input of specified

measuring variables under tag name. Specify upper and lower limits. Will evaluate how the

process is maintained by the student during the simulation. Evaluation criteria is whether

student is able to maintain process within specified limits.

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