What is the Method Statement for Flushing and Testing of the Gas Distribution Network?
The Method Statement for Flushing and Testing of the Gas Distribution Network involves a systematic process to ensure the integrity and safety of the network. Typically, it includes preliminary checks of the work area’s cleanliness, followed by the flushing process, where a specified flushing medium is circulated through the network to remove contaminants. The subsequent pressure testing involves subjecting the network to predetermined pressure levels to assess its structural soundness. Leak testing procedures, such as soap testing or electronic detection, are also implemented to identify and address any leaks.
Thorough documentation of the entire process, adherence to safety measures, and compliance with relevant standards are integral components of the method statement [1].
Table of Contents
Scope of Works
This method statement covers the contractual scope of work for flushing and testing of the gas network piping in the project in line with scope of work and particular conditions of the contract document.
Definitions
Construction Supervision Consultant (CSC)
Main Contractor
MEP Contractor
Gas Contractor
Supplier/Vendor – Seller of material as defined in project specification
Must – Signifies a legal or statutory requirement
Shall – Signifies a requirement made mandatory by this specification
May – Signifies a feature, which is discretionary in the context in which it is applied
Will – Signifies feature which the supplier may assume to be already present
SNG- Synthetic Natural Gas
LPG- Liquefied Petroleum Gas
NSNA-Notification to Start New Activity
PTW- Permit to work
MOP- Maximum Operating Pressure
References
Detail Design specification
Shop Drawings: Gas Network Overall plan drawing
IFC Drawings: Gas Network Overall plan drawing
NFPA 54: National Fuel Gas Code. 2011 Edition.
IGE/TD/3 Edition 4; 2005 -Steel and PE pipelines for gas distribution.
IGE/TD/4 Edition 4: PE and Steel gas services and service pipe work.
IGE/TD/3 Edition 4 Supp1 : Handling, transport and storage PE pipes and fittings.
IGE/SR/24: Risk assessment techniques.
IGE/SR/25: Hazardous area classification of Natural gas installations.
IGEM/TD/13 Ed 2: Pressure regulating installations for Natural Gas, Liquefied Petroleum Gas
and Liquefied Petroleum Gas/Air.
IGE/GU5 edition 2; 2005 – Procedures for managing new works, modifications and repairs.
ASME-Section IX: 2007 Boiler & Pressure Vessel Code
BSEM 1555 – (Suite of European specs for polyethylene Pipes)
IGE/SR/22: Gas Purging and Commissioning Method.
Abbreviations
HSE – Health, Safety & Environment
QC – Quality Control
MST – Method Statement
RSK – Risk
ITP – Inspection and Test Plan
PQP – Project Quality Plan
INR – Inspection Request
PPE – Personal Protective Equipment
MEP – Mechanical, Electrical & Plumbing
STARRT – Safety Task Analysis Risk Reduction Talk
Responsibilities
Project Manager
Project Manager (MEP) will be responsible to manage, execute, complete and handover the
construction activities within approved budgets and resources in compliance with Project
Requirements as specified in Project Specifications. He will be overall in charge of
implementing Method Statement in accordance with HSE requirements.
Construction Manager
Construction Manager will be responsible for managing construction activities and will lead
and communicate site Supervision, Subcontractors and Vendors to assist them in working to
the Project Schedule by conforming HSE requirements at site.
HSE Manager
HSE Manager will be responsible for plan, coordinate and implement issues and directives
within the organization. He ensures safe environmental working conditions for all employees.
QC Manager
QC Manager will be responsible for supporting the project team in implementing and
maintaining Quality Management System for the project through PQP, ITP, MST, and
Procedures in compliance with Project specifications, Codes and Standards.
HSE Officer
HSE Officer will ensure enforcement of safety procedures in accordance with the approved
HSE Plan. Will be closely monitoring the site engineer’s strict implementation of the MS and
Risk Assessment, the use of proper tools and equipment to maintain safety, certifications of
equipment and their adherence to safety regulations, reporting of any unsafe work or
stopping work that does not comply with HSE procedures.
Site Engineer
Site Engineer will be responsible for carrying out all construction related activities with
compliance to HSE and QAQC requirements as per contract specifications, drawings/documents, codes and standards.
QC Engineer
QC Engineer will be responsible for conducting inspections as per PQP.
Supervisor/Foreman
Supervisor/Foreman will be responsible for coordinating all works and workers related to job.
Electrician
Electrician/other tradesmen will be responsible in assisting his superiors during all
construction work related activities following HSE and QA/QC requirements.
Store-in-Charge
Store-In-charge receives and inspects all incoming materials and reconciles with documents;
processes and distributes documentation; reports, documents and tracks damages and discrepancies.
Interfacing with other Operations
Other Mechanical, Electrical and Plumbing works and Architectural, Civil and Structural
requirements
Duration, Phasing with the Subcontractors
All works associated with construction work referred to in this Method Statement shall be
completed as per project schedule.
List of Subcontractors
Subcontractors for MEP
Subcontractor for Gas Installation
Material Handling and Storage
During transport, handling and storage special care shall be taken not to damage the
materials. Materials shall be cleaned from any foreign matter deposited during transport.
All material storage locations should be on suitably firm, level ground, free from damaging
material with adequate access for construction vehicles and/or lifting equipment.
On receipt of ducts and accessories at site, necessary precautions shall be taken for
unloading, shifting, and storage as follows:
While unloading, shifting and storage, it should be ensured that there are no transit
damages.
Material Inspection
For materials to be inspected after receiving at site, the following points are to be
followed:
Each material item shall be allotted a distinct and separate reference number and
mentioned on material requisition.
Make sure that material is approved/examined by the Consultant and QAQC and
associated documents/test certificates are approved.
The Store In charge shall ensure that all approved supplies be delivered to site as per
the approved material submittal; with the manufacturer’s seals, labels or other proof of
origin intact.
The labels and seals shall not be removed until the material is required for use and shall
be retained for inspection by the Consultant and QA/QC.
Store-In-charge shall initiate material inspection for all incoming material to QA/QC and
the material shall be inspected against reference documents and as per approved
material submittal.
Moreover, the physical condition of the material shall be checked. Afterwards, an INR
shall be raised by QA/QC to Consultant and inspection will be carried out by Consultant.
Materials, which do not conform to the given specification/approved material submittal,
shall be rejected. Any discrepancy or damages will be notified and reported for further
action.
For any materials inspection, the items shall be segregated as per their type/sizes and
placed items separately.
Each item shall have an identification posted on a laminated paper with the description of
the items clearly written on it.
There shall be appropriate spaces between the material items so that the
engineer/inspector can freely go around them and inspect the materials thoroughly.
Staking the materials all over each other & in one corner is strictly not allowed.
All insulation material shall be stored in a dry place and adequate cover shall be provided to
ensure that they are not direct exposed to weather as per manufacturer’s recommendations.
Any discrepancies, damage, and etc. found to the materials will be notified and reported to
QA/QC Engineer and Project Engineer for further action.
Materials found not suitable for site use should be removed from site immediately.
Protect from water marks as any damage or water mark is not allowed during installation.
Resources
A. General Tools and Equipment
Tools
a. Mechanical Tool box consisting of Measuring tape, Spirit level, Wire cutter & Disc
cutter etc.
b. Hex blade with mounting bracket
c. PE Pipe Cutter
d. Cleaning Brush
e. Hammer
f. Chalk Liner
Screw Driver Set
Spanner Set
Note:
All testing equipment’s and measuring tools to be used shall have a valid calibration
certificates prior to usage.
All lifting equipment and machines shall be 3rd party verified with valid certificates.
B. Materials
Air Compressor
C List of Manpower
Construction Manager
Site Engineer
QC Engineer
HSE Officer
Supervisor
Foreman
Technicians
Helpers
Truck Driver
Mobilization
A. Preparation and Planning
The contractor shall ensure that all gate passes, permits, tools, materials for safety
precautions, manpower and equipment are available before commencement of work.
The Site Team shall make sure that access roads are always clear from any obstruction
and site is always accessible.
B. Site Clearance
Before commencing the work, the area shall be cleared of all debris, materials or other
obstructions.
C. Traffic Management
The Site Team with the assistance of the Safety Officers shall coordinate logistics and
materials movement through site following the direction and road signs displayed on site.
The required diversion routes shall be marked on drawings including the required traffic
signs.
The Work Permits and Operator Certificates shall be compiled and files for reference by
authorized personnel.
- Temporary traffic signs, barriers and flagmen will be deployed to control traffic flow in
accordance with and Traffic Management of the HSE Plan. - At the end of each ramp there will be a transition area to give the driver the opportunity
to watch the access roads before joining thereto.
D. Pre-construction Safety Meetings
Meeting shall be scheduled prior to the beginning of the work and before any Sub-contractor
starts on the project.
Safety awareness meetings will be conducted every working day morning/every other
day to brief the work force in the safety prevention measures. The equipment check for
safety shall be recorded/ documented during the daily Safety Awareness Meeting.
Traffic safety will be discussed to emphasize these meetings.
Each worker will be instructed to follow specific safety requirements related to his trade.
They will be required to follow installed safety signs, observe barricades and use PPEs.
The contractor safety officers will perform hazard risk analysis by identifying all steps, hazards
identified in those steps, with a focus on the relationship between the work task, the tools
and the work environment. After identifying uncontrolled hazards.
E. Operating Procedures
Site investigation has to be carried out to develop safety precautions and measures prior to
commencement of the work. After such investigation, relevant sign boards will be displayed
and barricades will be installed where and as necessary, such as but not limited to the
following:
Relevant information, advanced signs, warning and mandatory signs will be placed as
required.
Radio Communication system would be used where normal communication is
impossible.
After completion of the work, safety cones and barricades must be removed accordingly.
Methodology
Pre-Installation
All relevant documentation, approved shop drawings and material applicable to particular
section of works will be checked by Site Engineer prior to commencement of work.
Ensure that Material received is in compliance with the Project Specifications/Authorities
Regulations and is approved.
Ensure that all required materials and accessories are delivered, inspected and
approved by Consultant and are readily available at site to carry out the work.
Prior to commencement of work, areas and access will be inspected to confirm that site
is ready to commence the work and coordinated with other trades and subcontractors.
All relevant documentation (includes MST and RA are approved, obtain necessary work
permits, fill up STARRT cards after completion of daily tool box talk), will be checked by
Site Engineer prior to commencement of work.
The Site Engineer/Site Supervisor will give necessary instructions to tradesmen
(Mechanical/HVAC) and provide necessary approved construction/shop drawings.
The Site Engineer/Site Foreman will check that proper tools and equipment are available
to carry out the work and are in compliance with contract specification.
The Site Engineer will explain his team about HSE precautions to be observed.
The Site Engineer/Foreman ensures the cleanliness of area.
Flushing Activity
The objective of flushing activity to remove debris, weld slug and any other contaminant that
are present in the new installed pipeline.
Equipment for flushing
► Frist aid equipment
► Flexible hose; bcal supplied, mop: 20 bars (high pressure rated)
► Ball valves
► Compressor
► Digital pressure gauge; 0 to 20 bars
► Temperature gauges; 20c (+/-2c)
► Extended flushing pipe
► Transition fittings
9.3. Preparation Work Prior Start Flushing
a. Method statement and log for flushing shall be available during inspection.
b. Highlighted section of shop drawing shall be available during inspection.
c. Submit the IR to engineer prior to activity for inspection and approval.
d. Prior the flushing, the complete pipe work section should be clean and free from obstructions.
e. Install digital gauge at both side of purge point to monitor the pressure, and the pressure must be equal.
f. Additional purge valve and end cap required to installed prior to flushing.
g. Inlet line pressure shall be maintained at 2 bar by regulator and monitor by operator.
h. Back fill of the pipe work to be completed minimum required level, any portion of the pipe work that is not backfilled to be properly secured.
i. The sequence of flushing works shall be done separately for both the gas network one after the other.
j. Prior to starting the flushing, make sure that all main valves are in the open position and
boundary purges point closed position.
k. Pressurize the whole network.
I. Purge point shall be used for flushing purpose of gas pipe main line or service
line.
m. Open and close one by one the purge point valves with intervals 10 to 20 seconds until
free air coming out for 2 Continuous minutes or more, then close it and move to the other purge point valve in the loop.
Flushing Procedures
Flashing shall conduct one by one network, for review refer to attached plan drawing appendix D.
For Road E14
a. Before start the flushing check the all main valve and service valve no. MV.78.006, MV.78.008, MV.78.010, MV.78.011 , MV.78.005, MV.78.007, MV.7B.009, MV.78.012 are open position. and purge valve closed position. As well end capped.
b. Keep the compressor near to main valve no. MV.7B.006, open the purge point (006b) and connect to the compressor hose, pipe tools, regulator and digital gauge.
c. Digital gauge shall be installed at valve (006a) to monitor the pressure.
d. Install endcap with purge point at node number 7.0019, 7A.100 and 7B.023 refer to attached drawing.
e. Install end cap only for all the service line.
f. Ensure the prior to start the flushing all the valves shall be properly installed.
g. Start pressurization from valve (006b) until 2 bar is achieved.
h. Compressor will continue injecting pressure inside pipeline to maintain the pressure at 2 bar.
i. Once 2 bar pressure reached start flushing from the valve and by opening and closing the purge valve (013a) at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (013a).
j. Once the 2 minutes have passed without dust or debris, it means that the pipeline between the injecting and purging purge valve is clean.
k. After finishing the previous step, close the purge valve (013a).
I. After completed flashing between (MV.78.006) to endcap with purge pint (013a), start flushing from next point.
m. Compressor shall be same placed to pressurize the air for all flushing pipe.
n. Compressor will continue injecting pressure inside pipeline to maintain the pressure at 2 bar.
o. Start flushing fromanother place purge point by opening and closing the purge valve (014a). at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (014a).
p. Once the 2 minutes have passed without dust or debris, it means that the pipeline between the injecting and purging purge valve is clean.
q. After finishing the previous step, close the purge valve (014a).
r. After completed flushing the main network from (MV.78.006) to purge valve no. (13a) and (014a) and considered clean the pipe.
s. Start the flushing main from main valve no. (MV.78.006) to purge valve no. (01 Sa) shown in attached plan drawing.
t. Compressor continue injecting pressure inside pipeline to maintain the pressure at 2 bar.
u. Once 2 bar pressure reached start flushing from the valve and by opening and closing the purge valve no. (015a) at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (015a).
v. Once the 2 minutes have passed without dust or debris, it means that the pipeline between the injecting and purging purge valve is clean.
w. After finishing the previous step, close the purge valve (015a).
x. After flushed the main line network shall be flushing by service line as following below.
y. compressor position shall be same placed for all the Road E14 flushing, as installed main valve no. MV.7B.006, purge point (00Gb) connected compressor hose, pipe tools, regulator and digital gauge. As above ‘Y procedure.
z. Digital gauge installed at valve (006a) to monitor the pressure.
aa. Start pressurization from valve (00Gb) until 2 bar is achieved.
bb.Compressor will continue injecting pressure inside pipeline to maintain the pressure at 2 bar.
cc.Once 2 bar pressure reached start flushing from the valve no. MV.78.007 and by opening and closing the purge valve (007b) at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (007b).
dd.Once the 2 minutes have passed without dust or debris, it means that the pipeline between the injecting and purging purge valve is clean.
ee.After finishing the previous step, close the purge valve (007b).
ff. Repeat the (cc) step for all the following points sequentially.
gg. Valve no. MV.7B.008, MV.78.009, MV.78.010, MV.78.011, MV.78.012,MV.78.005 and purge point no. (008b), (009b), (010b), (011b), (012b),(005b).
hh.After flushing process completed, make sure that all the main line and service line valves are in the open position; and all the purge valves are closed except connected compressor before attempting to raise the line
pressure to the 6-bar test pressure (1.5 *MOP).
For Road 05
a. Before starting the flushing check all main valve and service valve no. MV.78.001, MV.78.002, MV.78.003, MV.78.004, MV.78.013, are open position. and purge valve closed position. As well end capped.
b. Keep the compressor near to main valve no. MV.78.002, open the purge point (002b) and connect to the compressor hose, pipe tools, regulator and digital gauge.
c. Digital gauge shall be installed at valve (002a) to monitor the pressure.
d. Install endcap with purge point at node number 7.005, 7A.001 and 78.008.4 (limit of work connection CP07B phase-1, limit of work connection CP07 A-1 Band limit of work connection CP02N) refer to attached drawing.
e. Install only end cap as per approved drawing prior to flushing.
f. Ensure the prior to start the flushing all the valves shall be properly installed.
g. Start pressurization from valve (002b) until 2 bar is achieved.
h. Compressor will continue injecting pressure inside pipeline to maintain the pressure at 2 bar.
i. Start the flushing first the main line pipe.
j. Once 2 bat pressure reached start flushing from the valve MV.78.002, to 7 A.001 limit of work connection CP07 A-1 B) and by opening and closing the purge valve (016a) at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (016a).
k. Once the 2 minutes have passed without dust or debris, it means that the pipeline between the injecting and purging purge valve is clean.
I. After finishing the previous step, close the purge valve (016a).
m. Once finish the flushing from MV.78.002, to 7A.001 limit of work connection CP07 A-1 B) start flushing another side. From main valve MV. 78.002 to node 7.005 installed endcap with purge point.
n. Compressor will continue injecting pressure inside pipeline to maintain the
pressure at 2 bar.
o. Start the flushing from node 7.005, purge point (018a).
p. Once 2 bar pressure reached start flushing from the valve MV. 78.002, to -7 A.005 limit of work connection CP078) phase 1, and by opening and closing the purge valve (018a) at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (018a).
q. Once the 2 minutes have passed without dust or debris, it means that the pipeline between the injecting and purging purge valve is clean.
r. After finishing the previous step, close the purge valve (018a).
s. once flushed the main line network shall be flushing by service line as following below.
t. compressor position shall be same placed for all the Road 05 flushing, as installed main valve no. MV.78.002, purge point (002b) connected compressor hose, pipe tools, regulator and digital gauge. As above procedure.
u. Digital gauge installed at valve (002a) to monitor the pressure.
v. Start pressurization from valve (002b) until 2 bar is achieved.
w. Compressor will continue injecting pressure inside pipeline to maintain the pressure at 2 bar.
x. Once 2 bar pressure reached start flushing from the valve MV.78.002, to 7b.00~.4 limit of work connection CP02N) and by opening and closing the purge valve (017a) at 10 to 20 second intervals until free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the purge valve (017a).
y. Once the 2 minutes have passed without dust or debris, it means that the
pipeline between the injecting and purging purge valve is clean.
z. After finishing the previous step, close the purge valve (017a).
aa. Repeat the (X) step for all the following points sequentially.
bb. Valve no. MV.78.001, MV.78.013, MV.78.003, MV.78.004, and purge point no. (001 b), (013b), (003b), (004b),
cc. After flushing process completed, make sure that all the main line and service line valves are in the open position; and all the purge valves are closed except connected compressor before attempting to raise the line pressure to the 6-bar test pressure (1.5 *MOP).
Procedure for Rectify If Flushing Works Fail
a. If the flushing works fail then the above procedure will repeat until the pipeline is clean.
b. The pipeline shall be considered clean and free from construction debris and foreign matters when free air with no debris or foreign matters keeps coming out continuously for 2 minutes or more from the applied discharge/vent purge valve. After the completion and acceptance of flushing activity, all the endcaps after service valves shall be installed with avoiding any dust, debris, weld slug or any other contaminant from entering the pipe.
Testing Activity
10.1. Materials and equipment’s for testing
► Frist aid equipment
► Flexible hose; bcal supplied, mop: 20 bar (high pressure rated)
► Ball valves; 41.2 bar
► Transition fittings
► Compressor; 180 CFM
► Digital pressure gauge; 0 to 20 bar.
► Temperature gauges; 20c (+/-2c).
► Pressure & temperature recorder; 100°c/16bar/24 hrs.
► Tent to protect from cold temp., dust and rain if required
► Barometer; (Meriam 750mm hg /20. 7°/43%.)
Manpower for Testing
Item Category Remarks
- Project Manager
- QA/QC Engineer
- HSE Engineer/Officer
- Engineer
- Foremen
- Skilled workers Technicians, Helpers, Pipe Fitter
- Laborers
- Joiners
- Flushing/testing engineer
Preparation work prior to start testing for Road E14 and D5
a. Safety briefing prior start work.
b. Safety signage shall be in place of testing.
c. Method statement and log for testing shall be available during inspection.
d. Highlighted section of shop drawing shall be available during inspection.
e. Make sure that the installation of pipes and valves has been completed, inspected
and accepted by Engineer. Including endcaps after the service valves.
f. Adequate barriers or other physical demarcation should be positioned at suitable
distance from the test site.
g. All caps, plugs, bends, tees and other fittings on mains incorporating flexible joints
shall be restrained against any movement during the test.
h. The trench shall be backfilled up to 200mm at least to secure the pipes in position
before pneumatic pressure is applied.
i. The sequence of testing shall be done separately for both the gas network one after the other.
j. All temporary piping, fittings, blinding, plugging and equipment fitted to the section of main under test shall be appropriately pressure rated to the test pressure.
k. Digital Gauges should be fitted as appropriate.
I. Where the main is exposed and accessible to the public, notices warning that pressure testing is in progress shall be prominently displayed and the area securely cordoned off.
m. Before final pressurization commences a visual check shall be made to ensure that the test section is secure for pressurization.
n. No person shall enter any excavation whilst the test pressure is being raised, the main is under test or the main is being depressurized.
o. Throughout the duration of the test, the system shall be examined at regular intervals to ensure that no hazard exists.
Testing
a. The test pressure shall be 1.5 times the maximum operating pressure (MOP) of the system which is 4 bar.
b. Any part of the supply network which is constructed, diverted, altered or renewed and cannot be included in a sectional or overall pressure test i.e. a final tie-in, shall be tested at the system MOP using leak detection fluid. Such occurrences shall be minimized and shall be approved by the Consultant.
c. The pneumatic test sets out to ensure that any leakage is within permissible limits (Permissible Pressure Loss).
The criteria for testing
a. That there will be a soak or stabilization period of at least 48 hours for the mains, before testing takes place.
b. The test duration shall be 24 hours after stabilization period.
c. The reference test temperature is taken as 20°C. (The temperature is likely to be higher than 20°C in which case the creep allowance provided will be higher. Refer to IGE/TD/3, Appendix 4).
d. It should be noted that a change of air temperature in the pipe of 1°C will result in a pressure change of the order of 23.331 mbarg.
Testing Procedures
a. As above shown in sketch for Pneumatic testing equipment.
b. Air compressor to compress the air pressure inside pipe.
c. Flexible hose to connect the air compressor to testing manifold.
d. Isolation valve to isolate the valve when required.
e. Pressure gauge for check the pressure reading.
f. Chart recorder for read I record the temperature.
g. Thermometer to sense the temperature.
h. Manometer for measuring the differential pressure.
i. the above sketch Main valve with two purge point have installed before flushing and testing.
j. Testing shall be conducting separately network gas pipeline Road E14 and Road D5.
k. Ensure that all end cap and taping tee with purge point installed, and purge valve should be closed position for whole network line.
I. Compressor and manifold arrangement should ready before testing. And keep near to main valve No. MV.78.006. for Road E14 and MV.78.002 for Road D5. For location of compressor refer to attachment No. D.
m. Connect the compressor to purge point isolation valve 02. Make sure isolation valve should be close position.
n. Prior to pressurizing gas pipe ensures that all the network pipeline main valve and service valve should be open position and all the purge valve closed position. Except compressor connected.
o. Installed pressure gauge above sketch.to read out the pressure inside the pipe and while pressurizing can check the how much pressure inside the gas pipe.
p. Open the isolation valve 01,02 shown in above picture and start pressuring through the purge point, air shall be under controlled condition into the service appropriate test is reached care shall be taken to ensure that the pipe work is not subjected to over pressurization.
q. After pressurized remove the air compressor and connect the chart recorder that same purge point which was uses for air compressor.
r. Keep the chart recorder near to same Main valve were used to pressurized.
s. Place the temperature sensor near the main valve which is coated wire. The coated wire further connected to the thermometer and chart recorder to measure the temperature sense by the temperature sensor.
t. The manometer which is wireless pressure sensor keep the near thermometer to measure the differential pressure.
u. Prior to pressure testing, the flushing is completed pipe work section and shall be cleaned and free from construction debris and foreign matter.
v. Immediately upon satisfactory completion of the tests, the whole of the main shall be subjected to a pneumatic soundness test at maximum working pressure 1.5* MOP.
w. Following the satisfactory completion of the final tests, the main shall be purged and connected to the live main in accordance with IGE/TD/3.
x. Mains which are not commissioned immediately following testing shall be pressurized and replaced with nitrogen reading for monitoring purpose.
y. Test instruments shall be fitted so that they can be read and operated without entering the trench or standing in line with the end of the main.
z. Air shall be introduced under controlled conditions into the main or service until the appropriate test pressure is reached. Care shall be taken to ensure that the pipework is not subject to over pressurization.
aa. Consideration should be given to raising the pressure in stages (i.e. 1 bar, 4 bar, 7
bar) to allow any tie-in joints to be progressively tested, using a leak detection fluid.
bb. No person shall enter the trench whilst the test pressure is being raised, during the test or whilst the main is being depressurized.
cc. Before the start of the test period the temperature of the air in the pipe shall be allowed to stabilize before the test period is commenced. This shall be indicated by a stable pressure reading.
dd. Stabilization period to be 48 hours after pressurizing.
ee. After stabilization period, pressure recorder, manometer, pressure gauges and thermometer shall be installed in the testing area. Then the 1st pressure reading shall be taken along with temperature and ambient pressure.
ff. After 24 hours (testing period), 2nd pressure reading shall be taken along with temperature and ambient pressure.
gg. Calculations of the allowed pressure drop to be taken in consideration following clause no. 8.9.
hh. If the pressure drops in allowed ranges, test to be success.
ii. When the test has been completed to the satisfaction of the Engineer, the air pressure shall be released through suitable vents in a controlled manner until the whole of the main is at atmospheric pressure.
kk. All calibration certificates for equipment, instrument, & machinery shall be submitted
prior to start flushing and pressure test works.
II. After completion of testing, a test form shall be filled and attached with related documents for engineer approval.
mm. The Consultant shall confirm by checking the gauges installed at all extremities that the pressure within the whole of the main has been reduced to atmospheric pressure.
The Consultant shall record this information on the test certificate before authorizing further work to proceed.
nn. For any test above, initiate the inspection notification to consultant/ engineer for witness and approval.
oo. Test shall be done with a chart recorder to ensure that pressure and temperature recorders having suitable range of values.
Rectification/Repair works and leak detection
Where the instrument reading after correction for barometric pressure and temperature
readings show a pressure loss greater than the calculated allowable pressure loss,
investigations shall be carried out to find the leakage:
- Due consideration should be taken of the pressure inside the pipe work under test and a
reduction in the pressure within the pipe work of 15% should be considered before carrying
out any examination of the pipe work. - All connections plugs and external fittings shall be re-examined for possible leakage by leak
detection fluid. Any leakage on a PE fusion joint should not be repaired and the joint should
be cut away and remade following main depressurization to atmospheric pressure. - Where an MP/IP PE main is to be retested following depressurization, it must remain at
atmospheric pressure for a minimum of three hours prior to re-pressurization, to allow creep
from the original test to relax. - If no obvious leakage path is found, a re-test may be considered appropriate.
- As appropriate, its necessary to divide the pipe work into sub-sections using pipe-cutting and
end caps; and to separately test each sub-section to determine the location of the leakage,
i.e. the main shall be divided into sections, each being tested separately, and the section
failing the test shall be further sub-divided until the location of the leakage is determined. - When all sources of leakage have been located and repaired, a further test should be carried
out on the complete section of pipe work. - If method of dividing sections didn’t work, other methods shall be used such as liquid gas or
any suitable method to find the leaks as per recommended in IGE/TD3/ Edition 4.
Health, Safety and Environment
A. HSE Risk Assessment
Please refer to attached document on Appendix A.
B. Permit and Licensing Requirements
The required permit to work shall be obtained prior to commencement of work. This shall be
coordinated with HSE. Site interfaces permit to be taken from another contractor before placing pipe at tie-in point to reconfirm IL and coordinates.
C. Pre-Start Safety Briefing Arrangements
C.1 Protective and Safety Equipment
All workers involved shall be equipped with adequate PPE as stated below:
Safety Helmet with Company Logo
Safety Boots
High Visibility Vest
Safety Goggles
Hand Gloves
Coveralls
Proper safety harness
C.2 Information to Personnel
Safety Induction
Job training
All the personnel involved in this task shall be provided training and only trained
personnel shall be authorized to work around this area.
Toolbox talks
STARRT Card
C.3 Special Safety Requirements
All necessary personal/protective equipment (PPE) as well as harness be provided.
Rigging Team, wearing distinctive vests, shall be assigned to help operators maneuver
their equipment.
The equipment operators shall possess the required licenses and certificates.
The required permit to work shall be obtained prior to commencement of work.
The project safety officer is responsible along with the project zone site engineer for
ensuring that all operations are carried out with due regard to the safety of all project
personnel & property.
Working at height to be monitored with due care.
In case of working at night, please refer to Method Statement for Night Works.
Contractor must provide a safe place of works, with safe access and egress. Provide as
safe working environment that is without risk to health.
C.4 Emergency Procedures
Quality Assurance and Quality Control
A. Quality Assurance Requirements
The contractor shall provide the required documents for Consultant’s approval prior to initiate with the execution of this activity as per project Specification.
The Quality Control requirement shall include related ITP’s and other related documents as applicable. Refer to Inspection Test Plan (See Attachment 8)
B. Quality Assurance Process
The contractor shall notify the Engineer 24 hours in advance prior to start of activity and Comments from the Site Instruction will be complied with the satisfaction of consultant.
The contractor shall consult the public utility authorities not less than one month before it is proposed to commence work to ascertain whether any underground installations will be affected by the proposed work, in which event the contractor shall make all necessary arrangements with the public utility authorities to safeguard the installation.
C. Follow up and Evaluation
Follow up on quality performance shall be carried out through in-house monitoring system
such as progress reporting to planning department, daily, weekly and monthly reports
generated by planning department to closely monitor site performance.
All the above shall be conducted in close coordination with the quality department to
monitor any deviations from the Quality Management System requirement and induce
corrective actions whenever required to eliminate non-conformance or quality deviations.
D. Records
Checklists (CKL)
Inspection Request (INR)
Inspection and Test Record (ITR)
Appendices
A. HSE Risk Assessment for Flushing and Testing.
B. Inspection and Test Plan for Flushing and Testing
C. Checklist for Flushing and Pneumatic Test form.
D. Plan drawing for Flushing and Testing &Compressor location.
E. Compressor catalogue.
Sources:
Written by:
Jose S. Villegas is a seasoned professional and civil engineer in the construction industry with over 24 years of experience. He has worked on various construction projects ranging from small to large-scale projects. He has a deep understanding of the construction process, from quality to implementation and completion.