Saturday, March 19, 2016 Newport County, Rhode Island, … MCA FCLC LNGF Gas Measuring...03 LNG...

Copyright © 2015 United States Maritime Resource Center, Inc. All Rights Reserved. 1Copyright © 2016 United States Maritime Resource Center, Inc. All Rights Reserved. 1

Flammable Cryogenic Liquid Carriers

Thank You to the Seminar Sponsor

Seminar Provider and Host

Saturday, March 19, 2016

Newport County, Rhode Island, USA


Agenda & Topics

Morning 0830 - 1230

01 Introduction

02 LNG Properties and Characteristics

03 LNG Hazards

04 LNG Industry overview

Afternoon

1330 – 1630 Interactive Work Shop

05 LNG Fuel Vessel Design and Construction

06 Fuel Tanks and Safety Systems

07 Gas Atmosphere Control and Monitoring, Venting,

Inerting, unique repair hazards


07 LNGF Gas Atmosphere Control & Monitoring

Unique HazardsEmptyingInertingPurging DryingGas Freeing Venting

Copyright © 2016 United States Maritime Resource Center, Inc. All Rights Reserved. 4

Exercise: Safe Working Practice

Required steps for replacing pressure gauge on LNG bunkering line:

Permit to work?

Risk Assessment?

Notification / Communication?

Block and Bleed?

Blank or Blind Flange?

Tools?

PPE?

Lock out / Tag Out?

Gas Testing?

Inerting?

Repair Procedure?

Calibration?

Inspection and Testing ?

What am I missing?


Emptying

• Requirement to empty, purge and vent independent of gas

consumers

• Must use the vessel piping system

–Tank and piping arranged to minimize pockets of gas or air

remaining

–Gas sampling points provided at the fuel tank

• Instructions must be available on board

• Always inert tank prior to venting

• Inert gas may be provided from an external source


Emptying Systems

• Open inlet valve to pressure build-up vaporizer to build system pressure

• Close inlet to gas heater vaporizer

• Open bunker line bottom fill, ESD and manual valves for discharge to shore facility

• Follow specific system procedures


Emptying, Inerting, Drying and Monitoring

Should be possible to empty, purge gas and vent bunker tanks with

the gas piping system

Should not be dependent on the gas machinery system

Procedures for emptying, purging and venting should be developed

Fuel gas storage and transfer systems must be kept dry to prevent

formation of ice in pipes , tanks and gas handling equipment

N2 supply should be equipped with dryer and dewpoint monitoring to

insure dry inert gas supply

Water vapor in piping systems can condense when cold gas is

introduced

Generally dew points below -40 C are standard for LNG piping and

storage tank drying


Inerting Systems (Atmosphere control)

8

IMO Interim Guidelines 2.9.2.6 : Bunkering lines should be arranged for inerting and gas freeing. During operation, bunker piping should be gas free.


Displacement and Dilution

LNG Shipping Knowledge, 2nd ed, SIGTTO

Displacement:

• Piston effect

• Displace air in tank by

maintaining inert gas /

air interface

• Theoretically uses less

inert gas (N2) – one tank

volume

• Low pressure maximizes

piston effect


Drying and Inerting

Inerting / Drying by Dilution:

Inert gas pressurized into tank

from N2 Supply inlet piping

The N2 will displace tank

atmosphere through vapor

return line to engine, shore tank

or atmosphere

N2 should be completely dry with

a dew point less than -40° C and

moisture content set point control

Monitor gas discharge methane

content to minimize methane

emission to atmosphere

Ideally burn gas in engine or

other consumer until all methane

consumed


Inerting and Purging System

Nitrogen is supplied from an N2 Generator

• Minimum Supply pressure 8.0 Barg

• Max supply pressure 8.5 Barg

• Capacity:

• Type:

Also supplies N2 for instruments

Connections are provided for shore supply of N2 at V62

N2 system is configured to provide automatic inerting to:

• Vapor Return Line V04

• Bottom Connection Line V21 (Supply Line to PGE and MGE)

• MGE Purge V23

• Engine Line V30 (GVU Purge)

• Bunker Line V55

Purge to shore V58 (Manually operated)


Fuel Tank Inerting

Bunker lines, Fuel tanks, and fuel

system piping provided with N2

connections

Purpose:

Prevent flammable atmosphere in

tanks and piping

Gas free prior to repair / drydock /

lay-up

Initial loading / return to service

Automatic purge on master gas

valve shutdown activation

Vapor Densities, kg/m3:

Methane: 0.668

Natural Gas: 0.700

Nitrogen: 1.165

Air: 1.205


Inerting• Ensure that O2 level is less than 2% before introducing methane

• Blow N2 through line to ensure dryness

• Test for O2 at supply sample / drain / vent valve

• Use N2 purge to test for leaks

• Timed N2 cycle based on pipe volume to be inerted can be used

NG VaporInert Gas

(N2)Air

Inert Gas (N2)

NG Vapor

LNG (Liquid)

NG Vapor

Inert Gas


Fuel Tank Inerting

N2 from ship or shore to

fuel tank via V04 and

V03 through vapor

return line

Follow vessel fuel

systems procedures

Displaced vapor can

forced through fuel

supply line until

consumed, or to shore

through bottom bunker

fill line, then vented

through vent mast

Follow with fresh air

when measurement

shows less than 1% LEL

for tank entry


Inerting and Purging System Arrangement

Nitrogen from an N2 Generator

–Operating pressure:

–Capacity:

–Type:

–Buffer tank capacity:

• May also supply N2 for valve

actuation

• Shore connection for external

supply

• N2 supply

– to liquid line via V57

–To vapor line via V53

–Tank bottom fill via V21 (NC,

manual)

–To boiler GVU via B V07

–To MEs via ME1-3 V07


Limitations on Fuel Transfer

IMO MSC 285 (86) Interim Guidelines:

2.8.1.6 Means that are not dependent on the gas machinery system

should be provided whereby liquid gas in the storage tanks can be

emptied.

USCG Policy Letter 01-15

g. Transfer of LNG from a vessel using natural gas as fuel

should not be conducted, except in the case of

emergencies that may endanger the safety of life, property,

or the environment, or as otherwise authorized by a COTP

for tank cleaning, repair, and similar procedures.

This guidance does not pertain to vessels that are built and

operated to carry LNG as a cargo.


Bunker Transfer by pressurization

46 CFR154.1838 Discharge by gas pressurization.

– The person in charge of cargo transfer may not authorize cargo

discharge by gas pressurization unless:

– (a) The tank to be offloaded is an independent tank type B or C;

– (b) The pressurizing medium is the cargo vapor or a

nonflammable, nontoxic gas that is inert with the cargo; and

– (c) The pressurizing line has:

• (1) A pressure reducing valve that has a setting that is 90

percent or less of the tank’s relief valve setting; and

• (2) A manual control valve between the pressure reducing

valve and the tank.


Bunker Transfer by Gas Pressurization

IGC 5.8.2

The procedure for transfer of cargo by gas pressurization should preclude lifting of the relief valves during such transfer.

Gas pressurization may be accepted as a means of transfer of cargo as long as the design factor of safety is not reduced during the cargo transfer operation.


33CFR127.203

• Marine transfer area to have at least two portable gas detectors

• Measurement from 0%-100% of LEL methane

33 CFR 127.205 Emergency Shutdown

–Must be able to be activated manually

–Is activated automatically when fixed sensors detect >40% LEL

• 33CFR127.207 Warning Alarms

–Rotating or flashing amber light

–Siren with sound pressure level of 125dB

–Not obstructed for distance of 1 mi (1.6km)

Portable gas detectors


Monitoring, Control and Safety Systems

Monitored Parameters:

Pressure when bunkering / transferring fuel

Tank rooms for liquid level and temperature, with alarms and automatic main tank valve closure

Monitor / Protection against fuel tank overfilling

Engine operation and mode indicators,

Gas extraction from lube and cooling systems

Gas detection in TCS, ducted piping, ESD protected machinery spaces, enclosed spaces containing gas piping or equipment

Fire Detection, tank room and machinery space

Operation and status of Ventilation system(s)


Monitoring & Control Functional Requirements

Interim Guidelines and IGF Code require Automatic Control, Monitoring, Alarm and Safety Functions to be provided for each component of gas fuel systems

Safety, reliability and dependability equivalent to conventional oil fueled vessel

Gas fueled vessel operations should always be within design limits and presetparameters for safe, reliable storage tank filling, fuel gas supply system and vessel operation

Ventilation, Detection and Safety shutdowns are arranged to deal with situations that occur too quickly for manual intervention

Design Philosophy: Safety shutdowns should not lead to an unacceptable loss of power or disabling other equipment

Automation, instrumentation, monitoring and control systems are to be provided to enable safe carriage, conditioning and use of natural gas, and to prevent venting.

Vessel and systems are arranged with sufficient redundancy to provide continuity of electrical and propulsion power

Single failure shall not lead to unsafe or unreliable situation


Gas Venting: Safety Relief System

Relief to aft vent mast

Bunker line vent valve

V05

N2 supply to relief vent

Tank safety relief V12 and V15

Vent and Safety relief from

fuel supply line

Tank vent valve V08

N2

supply to

vapor

return

V04

Bottom

and top

fill &

vapor

return

PBE Vent and Safety Relief V18

V19


Safety Relief

All pipelines and components which may be

isolated containing liquid gas should be

provided with relief valves.


Gas Venting


Unique Hazards: Gas Vent Sources


End of Section

Questions?

Saturday, March 19, 2016 Newport County, Rhode Island, … MCA FCLC LNGF Gas Measuring...03 LNG...

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Transcript of Saturday, March 19, 2016 Newport County, Rhode Island, … MCA FCLC LNGF Gas Measuring...03 LNG...