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Transcript of EIS_INSTALLATION OF METERING INSTRUMNETS ON FLARE PIPELINE
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Engineer In Society ( VAB 4042 ) Project Report
1
ENGINEER IN SOCIETY
INSTALLATION OF METERING INTRUMENTS ON FLARE
PIPELINE
BY
SitiHajarBintiJaafar( 9710 )
Emi ZurimaBinti Ismail( 9136 )
Nor WaniIdayuBintiAb Wahid ( 10266)
NurulZahidahBintiMdHasidin( 10809 )
Noor AzreenBintiMohdFaizol( 10902 )
April 2011
UniversitiTeknologiPetronas
Bandar Seri Iskandar
31750 Tronoh,
Perak DarulRidzuan
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EXECUTIVE SUMMARY
We started the case study by choosing the hot tapping project that had been
conducted at PETRONAS CarigaliSdnBhd, Peninsular Malaysia Operation (PCSB
PMO). The main objective of hot tapping is to install new flare meter at Resak and
Duyong flare header line at Onshore Gas Terminal (OGT) to calculate the amount of
product being flared because the quality and performance of plant is based on the value
being calculated.The few metering systems are installed at the flare pipelines without
any hazards to determine quantity such as Mass, Volume and Energy and quality of
material to be deliveredwithin specific uncertainty limits
The project took about a month to be done for specific pipelines at the PCSB
PMO. As the project being conducted, it must follow schedule which will be discussed
in detail in Work Breakdown and it shows how important project management is in the
every aspect of life especially in industrial world. Besides, precaution, safety aspects,
operating conditions and instruments have to be followed which will be discussed in
details in Health and Safety issues.
The scope of study for the hot tapping project is basically on how to conduct hot
tapping project in specific operating conditions at specific pipelines locations for the
OGT at PCSB PMO with Trisystems Engineering SdnBhd as contractor and TMM
Engineering SdnBhd as mechanical contractor
At the end of the project, the objective which is to install new flare meter at
Resak and Duyong flare header line at Onshore Gas Terminal (OGT) to calculate the
amount of product being flared because the quality and performance of plant is based on
the value being calculated,had been achieved successfully without any hazard occurred.
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TABLE OF CONTENT
Content Page
Executive Summary 2
Table of Content 3
List of Figures and Tables 4
Introduction & Background of The Project 5 - 6
Organization Chart
y PCSB PMOy Maintenance Engineering Departmenty Hot-Tapping Project
7
8
9
Environmental Impact 10Work Breakdown
y Project Life Cycley Logical Sequence of Activitiesy Level of Work Breakdown Structure
11
11 12
12 - 16
Activities Estimation
y Procedures
y Close-up procedures
17
18 - 26Cost Estimation 27 - 35
Scheduling 36
Health & Safety Issues
y Compliance to authority standards and guidelinesy Hazard Observation
37 38
38 - 40
Discussions & Recommendations
y Discussion of the outcomes
y Recommendationsy Conclusions
41 42
43
43
Appendices
References
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LIST OF FIGURES
Content Page
Figure 1: Organization Chart of PCSB PMO 7
Figure 2: Organizational Chart of Maintenance Eng. Dept. 8
Figure 3: Organization Chart of Hot Tapping Project 9Figure 4: Project Life Cycles Stages 11
Figure 5: Sequence of Activities vs Time 12
Figure 6: Level of Work Breakdown Structure 12
Figure 7: Fit-up Work 18
Figure 8: Leak Test on Welding Joint 19
Figure 9: Tightening and Untightening in cross sequence 20
Figure 10: Gaskets 20
Figure 11: Valve Installation 20Figure 12: Hot-Tapping Machine 21
Figure 13: Leak Test on Hot tapping Machine / Gate Valve 22
Figure 14: Fixing Pitot Drill and Boring Bit 23
Figure 15: Tightening Hot-Tapping Machine 23
Figure 16: Leak Test on Hot tapping Machine using Nitrogen gas 24
Figure 17: Cutter pass check, cutting travel measurement,alignment using manually
24
Figure 18: Hot Tap Perforation 25
Figure 19: Probe Installation 26
Figure 20: Exhibit 5 and Exhibit 6 34
Figure 21: Exhibit 7 and Exhibit 8 34
Figure 22: Scheduling 36
Figure 23: Fire Triangle 38
Figure 24: Possible gas leak identified and covered 40
Figure 25: Gas detector and Fire water 40
LIST OF TABLES
Content PageTable 1: Description on Project Managers Role 13
Table 2: Method of Magnetic Particle Inspection (MPI) 19
Table 3: Exhibit 3 29
Table 4: Exhibit 4 32
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INTRODUCTION& BACKGROUND OF PROJECT
Hot Tapping is the method of making perforation on the online line without the
interruption of emptying the section of pipe safely. This means the pipe can continue to
be in operation while maintenance or modifications are being done to it. The hot tapping
also used to drain off pressurized casing fluids. In this hot tapping, the heat must be
distributed to the flow to minimize the risk of explosion.
Hot tapping can be done to most any type of pipe, ranging from carbon steel to
PVC that contain water, oil, gases, fuels, steam and other chemical substances with
specific temperature and pressure condition.
Typical Hot Tap installation consists of a tapping saddle, gate valve, and Hot
Taping Machine. The installation is tested, the valve is opened, and the cutter and pilot
drill advanced. When the cut is completed, the cutter and pilot drill are retracted, the
valve is closed and the Hot Tap Machine is removed.[ i ]
There are three types of hot tapping which is tapping on tangential of pipeline,
tapping not on tangential (offset tapping), twisted and not on tangential of pipeline. At
OGT, there are two types of pipelines used which is High Pressure (HP) and Low
Pressure (LP) pipeline. For HP pipeline, the tapping types are flow transducers: offset
tapping, pressure transmitter: tangential tapping and temperature transmitter: tangential
tapping where for LP pipeline, the tapping types are flow transducers: twisted and offset
tapping, pressure transmitter: tangential tapping, temperature transmitter: tangential
tapping.
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In this report, basically we discuss on Hot Tapping and perforation (making
holes) that were done to the existing pipelines at Onshore Gas Terminal (OGT) in
PETRONAS CarigaliSdnBhd, Peninsular Malaysia Operation (PCSB PMO) to tie-in the
new nozzle installation. A few metering instruments such as flow transducers,
temperature transmitters and pressure transmitters are installed on the flare pipelines to
measure the flared gas to keep track on where the product goes and the percentage. The
operating condition during the entire hot tapping process must be monitored crucially as
the pipelines pressure must not exceed maximum gas pressure that will absolutely
contributed to hazard such as explosion and fire.
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Project Report
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ORGANIZATION CHART
Figure 1: Organization Chartof PETRONAS CARIGALI SDN BHD, PENINSULAR MALAYSIA O
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Project Report
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Figure 2: Organization Chart ofMAINTENANCE ENGINEERING DEPARTMENT
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Project Report
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Figure 3: Organization Chart of HOT TAPPING PROJECT
PROJECT MANAGER
Mr M Fallah bin Mohamedy To lead the project
and supervise thecontractor involved.
MAIN CONTRACTOR
TRISYSTEMSENGINEERING SDN. BHD(TRI)
y In charge on electricaland instrument part.
y Responsible to doinstallation of metering instrumentsand electrical.
MECHANICAL
CONTRACTOR
TMM ENGINEERINGy In charge on mechanical
part.y In charge on equipment.y Responsible to do welding
and perforation process.
C
PETRONASSDN. BHD (
y To pthe p
y To ley To o
appr proje
y To pof th
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ENVIRONMENTAL IMPACT
By performing a shutdown interconnect with low or high pressure system will
give an impact on environmental. Gas vented from the pipeline segment represents a
loss of product and an increase in methane emission. From the record, up to 6000 cubic
feet natural gas vented to make a new connection or non-leaking repairs.[ ii ]The
quantity is depends on pipe diameter, length between isolation valves and operation
pressure. For example, a shutdown connection on a steel can require one to three or
more days if pipeline outage and possible interruption of natural gas shipments in
addition to the release of methane to the atmosphere.
Methane is difficult to transport from its source. Generally it will be transported
in bulk by pipeline in its natural gas form. It is a relatively potent a greenhouse gas.
Compared with carbon dioxide, it has a high global warming potential of 72 (calculated
over a period of 20 years) or 25 (for a time period of 100 years). It is also affects the
degradation of the ozone layer. Large amount of methane are produced anaerobically by
methanogenesis. [ iii ]
So, hot tapping is an alternative technique that allows the connection to be made
without shutting down the system and venting gas to the atmosphere. With that, the
quantity of methane gas at atmosphere will be reducing. Hot tapping will avoided
cutting, realignment and re-welding of pipeline sections. It will also avoid inserting or
gas-freeing pipeline section for hot work. In other side, hot tapping also can reduce
planning and coordination costs.
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W ORK BREAKDO W N
Project Life Cycle
By general definition, project is taken to create a unique product or services where we
have to invest our time, money and resources in hope of a return. In the Hit Tapping
Project, four stages in sequence are done to follow the timeline. The four stages are:
Figure 4: Project Life Cycle Stages
Logical Sequence of Activities
In Hot Tap Project, each stage of life cycles is done by different types of team
according to their area of works. In defining stage, there are 3 minor stage will be done
which is inception, definition of project and proposal preparation which done by the
project manager. Organization chart of the project is created which included the main
contractor, mechanical contractor and the client. The job scope has been defined to all
members.
During planning stage, the Planning, Organizing, Leading and Controlling
(POLC) level is being used. The planning is satisfied by top management and completes
the strategies using the resources of time, money, team members, material of the
pipeline, installed instrument, drilling equipment, welding, and perforation process.
Leading is by directing each team to complete their jobs within time using motivating
2.PLANNING
4.DELIVERING
1.DEFINING
3.EXECUTION
ProjectLife Cycle
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methods and good communication skills. Finally, manager has to control the project
flow with respect to time, cost, and quality of the flared gas.
Execution stage is important because this is where the construction begins. The
metering instrument is installed regarding to the sequence and the drilling, welding, and
perforation process is done in safe environment by following the HSE standard. After
construction is done, we reach the final stage, delivering. This is where we handing over
the process of plant. The project life cycle is simplified in the diagram below:
Figure 5: Sequence of Activities vs Time
Levels of Work Breakdown Structure
Work breakdown is the schedule which guides all the teams to develop the project
according to the timeline. Work breakdown structure is divided into three main phases
which is Initiation Phase, Development Phase, and Procurement Phase.
Figure 6: Level of Work Breakdown Structure
WORKBREAKDOWN
Oganization
INITIATIVE PHASEProject Manager
DEVELOPMENT PHASEEngineer/Constructor
Electrical Mechanical
PROCUREMENTPHASE
Closure Phase
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To make sure that the yield flared gas, installation and perforation process of Hot tap
Project is follows the requirement and standard given, several task need to be completed
in sequence so that the project will complete before or on time.
1) Initiative Phase
This task is done by the project manager where he has to make sure that the
strategy chosen will be manage in sequence according to plan. The task of
project manager in initiative phase is described in the following table:
TASK DESCRIPTIONProject Initiation Initiation of project that fulfill clients need andstandard requirement.The client, PETRONASCarigaliSdnBhd want the project is done withoutshutting down the process of plant and the heat can bemeasured from digital meter installed on the pipeline.
Project Directive Basic direction of the project flow which includes thescope and procedure on how to complete the task.Thedirection is given including the duration of thedrilling, welding, installation and perforation process.
Project RequirementSpecification
Follow the standard and requirement highlighted byclient or project director to be completed bymanagement, design, engineering and constructionteams.Project manager will manage the flow of
project, electrical and mechanical engineering teamswill do the installation of metering instrument andconstruct the related equipment to the flare pipeline.
Project Management Plan Defines the objectives, scope for implementation,installation and the task responsible for each team.
Construction ManagementPlan
Build and develop the project according to therequirements in a manner rules for electrical andmechanical area.
Work Breakdown Structure Develop a structure for completing project accordingeach subordinate and working area.
Table 1: Description on Project Managers Role
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2) Development Phase
There are four main responsibility which is electrical and mechanical
engineering, inspection group, execution foreman and operations.
a) Engineering
Engineering responsibility includes design of nozzle and its support, type of
inspection of the parent wall for example, the radio graph and/or ultra-sonic
inspection, welding method and procedure, valve selection and specification
of test pressures, method of testing and the test media, appropriate drawingsand files up-dated. Special consideration must be given to testing media due
to parent wall temperature and thickness. The engineer or tapping technician
will assist other involved groups in the evaluation, planning, and execution.
The parent metal, at the immediate location of the hot tap, shall be inspected
prior to the welding of the nozzle onto the line, and vessel. The type, design
and temperature of the parent metal will determine the type of wall
inspection.The engineer will determine if Corporate Engineering Team
should be contacted. Typically, but not limited to, Corporate Engineering is
contacted prior to performing a high risk tap and/ or line plug for example,
lethal services, pressures greater than 1000 psig and/or temperatures greater
than 600o
F.
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b) Inspection Group
The Inspection Group which consists of the project manager and supervisors
representative will review and determine materials of construction, hot tap
location wall thickness. Inspection Group representative will also recommend
the welding method and procedure to the engineer. The Engineer will make a
decision concerning x-raying of the hot tap valve and any other special
testing or inspection requirements or procedures.
c)
Execution Foreman / Mechanical Planner The Execution Foreman / Mechanical Planneris responsible for all phases of
the planning, ordering, and execution of the job. In conjunction with the
Inspection Group the Execution Foreman / Mechanical Planner is responsible
for the proper inspection of the tapping and/or plugging machine, and
witnessing of all tests specified by Engineering.
d) Operations
The Operations Engineer/Planner are responsible for the initiation and
completion of the hot tapping data list used for preplanning and submitting
these sheets with the permit request. With assistance from other groups, as
required, the specification of department number, line or equipment number,
process conditions, justification and the safety review for a hot tap or plug is
also included in the client's responsibility. At the completion of the job, the
planner will send one copy of the completed data sheets to the responsible
mechanical engineer; including the recovered coupon.
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3) Procurement Phase
The Procurement phase is where the Hot Tap is installed based on the request
from the client after the Development phase completed. The quality of Hot Tap
on flare pipeline is monitored by the procurement team and construction
engineering team. Before Hot Tap is installed in real plant process pipeline, there
are several samples of Hot Tap being tested by the quality team during
experimentation. This is to ensure that the product does not have any issue in
terms of operations and functionality. The installation and perforation process
must be within the estimated cost and time given before the deadline to avoidany additional in cost and delay time to the client and plant process. If the
products are not settled at the agreed time between the company and the client,
there will be a penalty and bad reputation to the company. After the Procurement
phase and delivery of the products to the customer, the project comes to the
closure.Finally, in the Closure Phase under Procurement Phase, the Project
Manager issues the Project Closure report to the Corporate Engineering Team.
The details of the project are attached such as the documents related to the
project including the planning, designs, development and procurement. The list
of the items is mentioned in the handover checklist documents.
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ACTIVITIES ESTIMATION
This project can be generally classified to two major parts, Hot Tapping (welding,
installation of isolation valve and perforation of pipeline) and Installation of metering
instruments (Flow transducers, temperature transmitters and pressure transmitters.)
Procedures:
1. Pre-works
2. Hot tapping works
3. Leak test on welding joint
4. Valve installation
5. Preparation of hot tap equipment
6. Fittings of hot tap equipment on the valve
7. Leak test of hot tap machine set up using Nitrogen gas.
8. Cutter pass check and cutting travel measurement, alignment using manually.
9. Connecting high pressure air hoses between hot tap machine and power unit/air
compressor.
10. Hot tap perforation.
11. Bleeding off gas after first penetration and after perforation completion.
12. Releasing pressure from hot tap machine after completion.
13. Unbolting hot tap machine from tapping valve.
14. Probe installation
15. Housekeeping.
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Close-Up Procedures:
1. Pre-works
The pre-works are mobilization or demobilization of equipment, machinery and
manpower to site including loading and unloading, equipment inspection, refueling
diesels for gen sets and lifting activities using cranes.
2 . Hot Tapping W orks:
i. Fit-up: Fittings are measured and cut accurately to fitthe pipeline before
perforation. Pipeline is measured and marked to make sure the fittings areaccurately aligned to the pipeline.
Figure 7: Fit-up work
ii. Grinding: Pipeline is grinded before welding to remove paint and coating on
the welding spot.
iii. Welding: There are four phases of welding: Tark (welding points on the
pipeline just as markings of where should the nozzles will be welded), Root
Pass (welding around the nozzle circumference.), Hot Pass (several layers of
welding) and Buffering (final layer of welding)
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3 . Leak Test On W elding Joint
Welds are tested to make sure its robustness. One of weld tests is by using the
Magnetic Particle Inspection (MPI) technique to test the continuity of the
welding. There are two methods of MPI:
Using dry powder Using wet solutionCan be used directly even when thesurface is still hot.
Can be used to cold surfaces only (waituntil surface is cold).
Table 2: Method of MPI
Principle of MPI:
Figure 8: (a) no cracks/discontinuity (b) cracks/discontinuity on the welding
If there is no crack or discontinuity of the welding, the iron particles will be
attracted to the U-magnet. If there is discontinuity on the welding, the metal became lots
of magnets (poles formed magnets). The iron particles will not attracted to the U-magnet
but it will be attracted to the cracks. The tubing and fitting have to be check to make sure
they are properly fitted, control valve operational, ball valves and other venting outlets
are in close position and all bolts and nuts are in tight condition.
N S
N S N S
Iron particles Iron particles
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4 . Valve Installation
i. Tightening and untightening bolts in cross sequence.
Valve is installed on the branch fitting Nuts and bolts are put randomly.
Spherelwound gasket is inserted The bolts are tightened cross sequence.Figure 9: Tightening and untightening bolts in cross sequence
ii. Gasket
Gasket is chosen according to the pipeline size and type. In this project, we
use sphere wound andshould not have scratch to ensure no leakage
Teflon sphere wound gasket Graphite sphere wound gasketFigure 10: Gaskets
iii. Valve installed as isolation valve : Ball valve class VI is used
Figure 11: Valve Installation
HP pipeline
LP
Ultrasonic Flowtransducers point
Pressuretransmitter
point Temperaturetransmitter
point
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5 . Preparation of Hot Tap Equipment
Visit TMM Engineering Sdn. Bhd. to check the operation of the hot-tap equipment.
Tests conducted during the inspection.
Equipments used:
i. Hot tapping machine
Hot tapping machine
The pilot drill for the hottap machine T-101
Coupon cutter 1 drilling bit
2 drilling bit drilling bitFigure 12: Hot Tapping machine
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Tests conducted:
i. Leak Test of Hot Tap Machine/Gate Valve
1.
Hot tap machine T-101 is the smallest hottap machine. The drilling machine ismounted to the metal disc as a replacementto the hot tap valve.
2. Hot tap machine T-101 assembly isconnected to the nitrogen gas tank for leak test.Nitrogen gas is used because it is nothydrocarbon gas and cannot produce fire.
3. Pressure supplied is for testing is about 5 bars. This pressure must maintain for about5 minutes to show that there is no leak onthe machine.
4. Snoop liquid which is a soap based liquid isapplied at the mounting point to test if thereis leak
5. Snoop is applied to the marking area tocheck whether there is leakage.
6. Snoop liquid: leak detector
Figure 13: Leak Test of Hot Tap Machine/Gate Valve
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ii. Fixing of pitot drill and boring bit
Drilling bits are attached to the hot-tapping machine. We run the hot tap
machine and observe the movement of the drilling bit. The drilling bit
will be adjusted until it rotates straight on the exact point to ensure
accurate drilling point.
Figure 14: Fixing pitot drill and boring bit.
6 . Fittings Of Hot Tap Equipment On The Valve
Hot tap machines are tightened to the valves before any perforation done on the
pipeline.
The hot tapping machine ismounted in the valve.
Tightening the hot tap machine by cross sequence.
Figure 15: Tightening Hot Tapping machine
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7 . Leak Test of Hot Tap Machine Set Up Using Nitrogen Gas.
Nitrogen gas is injected for leak test and to vent out oxygen gas.
Hot tapping machine is powered by pneumatic. Genset supplies = 7bar
Masking tape is wrapped aroundthe mounting between the hottapping machine and the valve.
Nitrogen gas injected 2.5 bars. Pressureinjected must be higher than operating
pressure in the pipeline. . Pressure of thegauge drop indicates leak of the hot tappingmachine.
Figure 16: Leak Test of Hot Tap Machine Set Up Using Nitrogen Gas.
8 . Cutter Pass check and Cutting Travel Measurement, Alignment using
manually.
Height of the valve and branch fitting ismeasured. Travel length is the length for the drilling bit being screwed up/downduring and after perforation.
Alignment of the boring bit isadjusted according to the travellengthto make sure that drilling bit istaken out without being stuck whenthe isolation valve is closed after
perforation is done.Figure 17: Cutter Pass check and Cutting Travel Measurement, Alignment
Nitrogen gas injected=1.1 x operating pressure
Cuttingtravel length
Marking line forboring bit.
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9 . Connecting high pressure air hoses between hot tap machine and power
unit/air compressor.
10. Hot tap perforation.
A non-hydrocarbon gas, Nitrogen gasis injected to suppress oxygen in the air to
eliminate one element of the fire triangle.
Before perforation:
Valve is in open position. Then, Nitrogen gas is injected to the hot tapping
machine after it is mounted to the isolation valve.The bleed valve is opened;
Nitrogen gas is injected again for about 2 seconds to purge out the natural gas
inside the valve chamber that may contain oxygen which can cause explosion.
Bleed valve is closed, nitrogen gas supply stopped. Nitrogen gas inside the
chamber is 2.5bar.Perforation is done.
After perforation:
Perforation is confirmed when pressure on the gauge drops to atmospheric
pressure.Drilling is complete when the hot tapping machine reached marked link.
Pipeline is tapped. Tapping is confirmed when pressuredrops. From 2.5 bars on the hottapping machine gauge. The pressureafter tap is the pipeline pressure
Figure 18: Hot Tap Perforation
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11. Bleeding Off Gas AfterFirst Penetration and After Perforation Completion.
12 . Releasing Pressure from Hot Tap Machine After Completion.
13 . Unbolting Hot Tap Machine From Tapping Valve.
14 . Probe Installation
Temperature transmitter Flow transducer (horizontal) Sensor element (horizontal)
Flow transducer (vertical ) Sensor element (vertical) Pressure transmitter
Flow computer Flow computer Figure 19: Probe Installation
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15 . Housekeeping.
COST ESTIMATION
Operators can assess the economics of performing a hot tap as an alternative to a
shutdown connection by following the five steps below:
Five Steps for Assessing Hot Tap Economics:
i. Determine physical conditions of existing line.
ii. Calculate cost of performing a shutdown interconnects.
iii. Calculate the cost of a hot tap procedure.
iv. Evaluate the gas savings benefits of hot tapping.
v. Compare the options and determine the economics of hot tapping.
Step 1: Determine physical conditions of the existing line.
To ensure safety and as a preparation of hot-tapping project, operators need to
determine the maximum operating pressure (during the hot tap), type of pipe material
(steel, cast iron, plastic), condition of the parent pipeline (internal/external conditions
to evaluate include the location of nearby valves for emergency and corrosion, wall
thickness) to assure a safe project, location of nearby valves for emergency isolation in
the event of an accident, desired tap diameter depends on size of pipeline involve,
working space around the connection, location of other pipeline welds and
imperfections or obstructions. Operators should also determine if the line is looped,
as many gas transmission companies avoid operational disruptions by shifting the load
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to a parallel line. It is advisable to develop and follow a written plan to assure full and
proper evaluation of a future connection.
Step 2 : Calculate cost of performing a shutdown interconnect.
To tap a new point on a pipeline, there are two options, either to shutdown
interconnects or keep the pipeline online while hot-tapping is done.Thus, it will be
important to calculate the cost of both options. The cost of an actual project would
include Direct costs ( Material and equipment, welding requirements, quality control,
blow down and purge costs, labor, and scheduling expenses) and H idden costs ( Costof shut-off valves, advertising if service is to be interrupted, relighting of customer
services, and excavating for stopples and purge connections). Operators would be
advised to reference historical data to determine these costs. For the purposes of this
scoping analysis, material and labor costs for cutting out the line section and welding
in a tee connection in the shutdown method are assumed to be comparable to the cost
of welding on the fitting and performing the hot tap when the branch connection is the
same size as the pipeline. However, the costs of the gas lost through venting and inert
gas purging are unique to the shutdown interconnect.The formulas used to determine
the cost of a shutdown interconnects are shown in Exhibit 3. For these calculations,
low pressure is defined as less than 2 psig.For comparative purposes, calculating the
cost of a shutdown interconnects should take into consideration a multiple-project
scenario. This multiple-project perspective allows for a more complete comparative
cost analysis given the up-front capital costs of owning and operating a hot tap
machine and the need to perform several interconnections throughout a given year.
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Exhibit 4 illustrates how the cost calculations in Exhibit 3 can be applied in a
multiple connection scenario. The hypothetical situation presented includes several
projects on pipelines of various sizes and pressures. Cost calculations, however, are
only provided for the 4-inch pipeline scenario and only cover direct costs.
Exhibit 3 : Calculating the Cost of Shutdown Interconnect
Given:D = diameter of pipeline (inches)T = taphole diameter (inches) - for low pressure shutdown with tapholes for stoppersL = length of pipeline between tapholes (feet) - for high pressure shutdownP = line pressure (psia for low pressure, psig for high pressure)
Ppgas = current purge gas market price ($/Mcf) - assumed $4/Mcf Pg = current gas market price ($/Mcf) - assumed $3/Mcf Ce = cost of extra excavation, use company records ($)Cp = cost of purge connections and excavationCs = cost of hidden shutdown expenditures, see Appendix ($)Cf = cost of fittings, see Appendix ($) Time Taphole is open = from prior experience (minutes)
Calculate Direct Costs:
1. 2 . 3 . 4 . 5 . 6 .
7 . =
8 . Calculate Indirect Costs:1. Calculate Ce = cost of extra excavation for tie-in ($)2. Calculate Cp = cost of purge connections ($)3. Calculate Cs = cost of hidden shutdown expenditures ($)4. Calculate Cf = cost of fittings ($)
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Table 3: Exhibit 3Additional factors that are company specific include gas leakage past the pipeline
valves on both ends of the shutdown, number of stoppers, tap holes for venting and
purging, and type of purge gas. Leakage is particularly important as large pipeline block
valves can leak significant volumes of gas because they are used infrequently and the
valve seat can accumulate debris that inhibits a tight seal. The volume of leakage is
highly variable, dependent on valve type, age, pipeline pressure and service (dry gas
causes much less corrosion and accumulation of debris than wet gas). If a partners
individual evaluation following this lesson learned results in marginal economic
justification, then company experience on pipeline valve leakage 9 should be factored in
to improve the economics.
Step 3 : Calculate the cost of a hot tap procedure.
When comparing the up-front costs of hot tapping with shutdown interconnects
the only significant difference is the cost of the hot tap equipment. The tee fitting or full
encirclement sleeve and the valve have nearly the same cost for either method when the
branch is essentially the same size as the pipeline. The cost of welding a full
encirclement sleeve is nearly the same as the cost of welding a tee fitting in a line.
Labor cost for cold cutting the pipeline and hot tap cutting out a coupon are
sufficiently close for this type of feasibility evaluation. Maintenance costs apply only to
hot tap equipment, such as drill sharpening and other equipment care and replacement.
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Tapping machines come in several sizes, and a single machine can perform hot taps
from 3 to 12 inches. Less expensive machines can be purchased to perform small taps. In
general, capital costs for purchasing the hot tap machines typically used by gas
companies for the most common sized connections range from $13,200 to $23,000.
Equipment cost is normally a one-time capital expenditure and can be
depreciated over the life of the equipment, typically 15 to 20 years. Each company,
however, should calculate the depreciation in the same manner used for other equipment
purchases. This should be considered in conjunction with how often the machine will be
used in the future. To make this determination, operators should look at companyrecords to determine the number of times similar connections have been performed.
Typically, a company that performs several hot taps a year will find it economical to
own the equipment, especially in sizes up to 12 inches, and to maintain trained personnel
to perform the service. These jobs are usually simpler and require less specialized
training than larger hot tap jobs. For larger and less frequent hot taps a company might
consider it more cost effective to hire a contractor who will supply the equipment and
trained personnel. Most hot tap vendors will supply all necessary tapping equipment,
including the drilling machine, fittings, valves, cutters, and repair services. The majority
of vendors also offer contract services for larger or infrequent jobs, or will rent out the
tapping equipment. Supplying support services, such as excavation, welding, and cranes,
can reduce the costs of using an outside contractor.
Other factors, such as the line material and thickness, system pressure, and
temperature, should also be considered when determining the alternatives of purchasing
hot tapping equipment or hiring contractors. A company should evaluate how often the
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tapping equipment would be used and if they would realize savings by owning and
maintaining the equipment and training operators.
Exhibit 4 : Hypothetical Scenario and Example Calculation of Lost Gas andPurge Gas Costs for a Shutdown Interconnect
Given: A pipeline company requires numerous shutdown or hot tap connections asfollows: Pipeline Diameters, Inches 4 8 10 18 Pipeline Pressures, psig 350 100 1,000200 Pipeline Lengths1, miles2 2 1 3 2 Annual Taps3, number 250 30 25 15
(2 ) Calculate: Vpgas = Volume of Purge Gas 4
(3 ) Calculate: Value of Gas Lost by Shutdown Interconnects (Including PurgeGas)Calculate: Value of Gas Lost by Shutdown Interconnects (Including Purge Gas)
Cost = $74 for each of the 4 inch pipeline shutdown interconnects
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Table 4:Exhibit 4
The procedures described above are general guidelines for preliminary economic
assessment and can differ from company to company. Additional factors that are
company specific include gas leakage past the pipeline valves on both ends of the
shutdown, number of stoppers, tap holes for venting and purging, and type of purge gas.
Leakage is particularly important as large pipeline block valves can leak significant volumes of gas because they are used infrequently and the valve seat can
accumulate debris that inhibits a tight seal. The volume of leakage is highly variable,
dependent on valve type, age, pipeline pressure and service (dry gas causes much less
corrosion and accumulation of debris than wet gas). If a partners individual evaluation
following this lesson learned results in marginal economic justification, then company
experience on pipeline valve leakage 9 should be factored in to improve the economics.
Exhibit 5 presents ranges of hot tapping costs for both equipment purchase and
contracted services. The cost ranges shown include all materials; additional expenses
will result from labor and maintenance expenditures, as discussed above. Vendors state
that the operations and maintenance (O&M) costs can vary greatly, depending on the
number of taps performed and equipment and procedural care.
Exhibit 6 shows the equipment, O&M, and contractor services cost to per-form
the 320 taps per year in the hypothetical scenario first described in Exhibit 4. The
assumption is made that the 4, 8, and 10 taps (a total of 305 taps) would be
performed by the company. Because few taps equal to or larger than 18 inches are
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performed each year, these taps (a total of 15 taps) would be contracted to vendors. The
equipment cost includes the purchase cost of two small (
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Figure 21: Exhibit 7 and Exhibit 8
Step 5 : Compare the options and determine the economics of hot tap-ping.
The economic analysis shown in Exhibit 8 compares the significant cost and
benefit differences between hot tapping and shutdown interconnections for the
hypothetical scenario of 320 taps per year. The significant costs are the purchase,
operation and maintenance of hot tapping equipment and/or contracting for hot tapping
services. Here, both costs are included: the purchase of two hot tapping machines for
$36,200 for the smaller sizes and contracting the 15 large taps at $37,500 per year. The
purchased hot tap machines are operated and maintained at $5,500 per year. All these
costs are calculated in Exhibit 6. Many expenses, including the cost of fittings, valves
and basic labor, are assumed to be similar in both hot tap and shutdown procedures, and
can be excluded in the comparative analysis. A more complete analysis can be done by
evaluating and including the company specific hidden costs per Exhibit 3.The
significant benefit differences are the reduction in natural gas loss by eliminating
venting and the inert purge gas used in the shutdown interconnect procedure. As
summarized in Exhibit 7, annual natural gas savings total 24,440 Mcf for the
hypothetical hot tapping scenario, worth $73,320 per year at $3 per Mcf gas price. The
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annual inert gas savings of 1,710 Mcf is worth $6,840 per year at $4 per Mcf of
nitrogen, for a total annual benefit of $80,160.
In conclusion, hot tapping has been found to be more cost effective than
shutdown interconnects. Even when the system must be taken out of service, hot tapping
presents opportunities for both time and cost savings. While hot tapping is a by
companies for reasons other than the gas savings, consideration of the methane reduction
benefits can often serve to justify hot tapping over the shutdown inter-connect procedure
in a variety of circumstances.
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SCHEDULING
Figure 22: Scheduling
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HEALTH & SAFETY ISSUES
Hot taps are permissible only as a last resort, i.e. when safety, the time required
and/or expense of isolation and decontamination is unreasonable or either of the
preceding are less safe. If the facility is a covered process as defined by OSHA
1910.119, then the sites Management of Change (MOC) Procedure must be
followed. If a facility is not a covered process then an appropriate safety
review/audit should be performed prior to the execution of the hot tapping/plugging.
A special permit is required for all hot taps according to Safety Procedures, Fire
Permits and Vessel Entry/Fire Permits.
Compliance to Authority Standards and Guidelines
There are several authority standard and guidelines to follow in completing this
project. A lot of safety precautions to be take into account. The standard and
guidelines are;
A. Contact Safety for Sniff Test
B. Permits required are Special Permit, Entry Permit (Vehicle),Welding
Machine, Hot Tap Machine and Other machines or power equipment.
C. Special Safety Requirements are Two (2) points of egression, Sewers in the
area covered, Trapping required to retain welding sparks, Two (2) fire
extinguishers at the Hot Tap site, Periodic Sniff Test, Area enclosed with
barricade tape and Scaffolding if required
Please note that providers must be accredited by the Qualifications Authority, or an
inter-institutional body with delegated authority for quality assurance, before they
can report credits from assessment against unit standards or deliver courses of study
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leading to that assessment.[ iv]. All hot taps should be designed, fabricated, inspected
and tested in accordance with the applicable Codes and Standards. The applicable
standard for pressure vessels is usually the National Board Inspection Code (NBIC)
or API Standard 510, Inspection, Repair, Alteration and Re-rating of Pressure
Vessels. These Codes or Standards require that the design of the hot tap should also
be in accordance with the original code of construction. In most cases in the US, this
is typically the ASME Code Section VIII Division 1. In addition, API Recommended
Practice RP 2201, Procedures for Welding or Hot Tapping on Equipmen t in
Service, should also be followed [ v]
Hazard Observation
Hot tapping have an explosion hazard. Gas can ignite, causing explosion, death or
serious injury. Tapping into pipe under pressure can cause severe injury if safety
procedures are not followed. No person should make a hot tap unless that person has
been trained and qualified in the use of equipment. Welding is one of element in this
project, but it is the most crucial part of the project. This is because welding involves
heat, hydrocarbon element in the pipeline and also oxygen gas available in the
pipeline. Any carelessness may cause flame/explosion as all the elements in the fire
triangle are available.
Figure 23: Fire Triangle
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To prevent explosion happen, consider the fire triangle. We must eliminate at least
one of the factors to prevent fire which are flammable materials in the equipment,
combustible materials in the equipment and flammable gas in the atmosphere.
Fire Triangle elements;
i. Oxygen
a. Atmospheric air contains 20.9% oxygen
b. Maintain physical separation between air and fuel as far as
possible
c. Use line packing concept whenever there is a breach of the
physical barrier
i. Pressurize containers such that oxygen cannot step in
ii. Blanketing
ii. Fuel
a. Always present in hydrocarbon and petrochemical facilities
b. Detection methods used to monitor leakages of fuel
iii. Ignition Source
a. Energy is used to operate equipment in the plant
b. Contained based on standards used to define the hazards of
ignition in the plant
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Fi 24: poss i l gas l ak i ti i and covered
Figure 25 : (a)Surround ing LEL iden ti ied us ing gas de tector
(b) F ire wa ter is ready in case of emergency.
Safe ty Precau tions before we lding works are ;
i. Close / cover a ll poss i b le gas leakage /source
ii. Make sure tapp ing po int is far enough from poss i b le leakage source
iii. Iden tify w ind d irec tion by observ ing w ind sock. W ind may br ing gas
leakage to the we ld ing area and cause f lame
iv. Always measure lower exp los ion limit LEL leve l us ing gas de tec tor
v. Always make sure that f ire wa ter is ava ilab le when needed in case of
emergency
W ind sock
Poss i blegas leak
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DISCUSSIONS& RECOMMENDATIONS
This last chapter will give the big picture for the hot tapping projects outcomes,
necessary recommendation and conclusion.
Discussion of the Outcomes
Each year pipelines typically undergo several transformations. Performing hot taps to
make these connections and installations can reduce methane emissions from
pipelines and increase savings and efficiency. The following are several lessons
learned offered by partners and hot tap vendors:
1) Hot tapping has been performed by transmission and distribution companies
for decades. By evaluating the gas savings associated with this practice, hot
tapping can be used in many situations where it would not ordinarily have
been used
2) The site for the branch weld must be free of general corrosion, stress
corrosion cracking, and laminations.
3) Hot tap should not be performed immediately upstream of rotating equipment
or automatic control valves, unless such equipment is protected from the
cuttings by filters or traps.
4) For tapping on steel pipes, fitting generally consist of a welded branch
connection. However, when tapping into cast iron, asbestos cement, or
concrete, the fitting cannot be welded onto the existing header. Alternative
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fitting attachment techniques, such as a split cast iron compression sleeve or a
mechanical joint saddle, must be employed
5) For plastic systems, the operator should ensure that the hot tapping fittings
are compatible with the type of plastic pipe in the system and appropriate
joining methods are used. Vendors can supply suitable fittings and tools for
almost every kind of plastic system
6) If hot tapping has not been performed in the past, hot tapping procedures
should be developed and personnel trained. Be sure to include instructions
concerning possible burn through or hydrogen cracking during welding
7) All equipment must meet minimum industry and federal standards for
pressure, temperature, and operating requirements
8) If conditions of temperature, pressure, pipe composition, or tap diameter are
encountered that are unusual for your system, be sure to consult the
manufacturer of the tapping equipment or fittings
9) Industry and federal codes and standards should be consulted for more
specific specifications
10) Record emissions reductions associated with using hot taps and submit them
with your Natural Gas STAR Annual Report
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Recommendations
A decision on whether hot tapping is to be applied shall be based on careful
considerations including at least the following aspect which are;
Safety
Condition of the pipe/equipment under consideration
Configuration of the connection
Code/statutory requirements
Operating conditions
Technical capabilities of the drilling equipment under the operating
conditions (pressure, temperature, nature of product)
Related welding problems
Economic aspects
Environmental/pollution aspects
If hot tapping is to be applied under conditions approaching the technica l or
operational limits, specialist advice should be sought
Conclusion
Hot tapping is potentially hazardous and therefore should only be undertaken when
continuity of service is essential or shutdown of the system is impractical and when it
is shown to be technically feasible and to offer a clear advantage over alternatives.
The advantage may be economic and, in some situations, the safety and
environmental risk may be less than those associated with more conventional
methods.
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APPENDICES
Appendix i: Hot Tap Metering Installation Work Breakdown Structure
Hot Tap Metering Installation W ork Breakdown Structure
1.1.1Product Requirement
Specification
1.2.1Project Management PlanChecklist 1.2.2Project Estimation
1.1Project Directive1.2Project Management Plan 1.2.3Issue Management Plan 1.
1.2.4Risk Management Plan 1. Initiation 1.3Configuration Management 1.3.1Document Master Checklist 1.3Phase Plan
1.4Project Timeline 1.4.1Work Breakdown Structure 1.
2.1.1Schematic Block Diagram2.1.2Bill of Material
2. Development 2.1Electrical 2.2.1Industrial DesignPhase 2.2Mechanical 2.2.2Drilling and Welding 2
Hot TapMeteringInstallation 3.Procurement 3.1Supplier Management Plan 3.1.1Scope of Work
Phase 3.2Procurement 3.1.2Requisition of Order 3.1.3Puchase of Order 3.1.4Quotation3.1.5Delivery of Order 3.2.1Samples Prototype
4. Closure 4.1Project Closure Report 4.1.1Compile All Related Document 4.1Phase
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REFERENCES
iwww. koppl .com/pdfs/ Hot tap.pdf
iihttp://www.globalmethane.org/documents/events_oilgas_20090127_techtrans_day2 _robinson3_en.pdf
iiihttp://en.wikipedia.org/wiki/Methane
ivhttp://www.nzqa.govt.nz/nqfdocs/units/pdf/10983.pdf
vhttp://www.carmagen.com/news/engineering_articles/news38.htm