What is the method statement of LPG?
The method statement of LPG defines the installation including testing & commissioning works for the LPG system. This methodology ensures that all works are carried out in a safe manner, with quality, specifications, and approved shop drawings.
What is an LPG system?
An LPG system is a system that uses liquefied petroleum gas (LPG) as a fuel source. LPG is a flammable mixture of hydrocarbon gases, primarily propane, and butane, which are stored in liquid form under pressure. LPG systems are commonly used in vehicles, residential and commercial heating, and cooking appliances. LPG is considered a cleaner burning fuel compared to gasoline or diesel, and it emits lower levels of harmful pollutants such as carbon monoxide, particulate matter, and nitrogen oxides.
Table of Contents
References
Installation of the LPG System shall be in line with the following specifications:
NFPA 54, 58
Project Specification
Manufacturer Recommendations
Approved Shop Drawings, Material Submittals
IFC drawings & Materials
Approved Project HSE Plan, Emergency Response Plan, Waste Management Plan
Access
Works will be started or carried out only when all associated main contractors’ procedures are completed and by ensuring safe access to work areas will be available through hoist lifts/access ladders to carry out the work where ever main contractor site engineer’s & safety officers clearance available.
Logistics
MEP subcontractor will deploy a dedicated team for the required logistics and material movement in–out of the Project
Health & Safety Hazards
MEP subcontractor will comply with all safety measures as applicable to the project’s main safety requirements and follow approved HSE plans.
1. Working in extreme weather conditions
2. Night works
3. Use of temporary electrical supply
4. Loading and offloading of materials at the site
5. Using mobile equipment for the transfer of materials to the work locations
6. Improper stacking of materials
7. Use of power tools for the installation of the LPG piping
8. Manual handling
9. Use of scaffold, Working at Height, Use of ladders
10. Flushing of LPG line using Nitrogen
11. Pressure testing of the LPG pipeline
12. Painting of LPG pipeline
13. Improper housekeeping
Permits and Certificates:
HSE Permits and Certifications (as per activity requirements) – These should correlate with the activity Risk Assessment.
Permit To Work (Prior to starting an activity):
- Ensure obtain the necessary PTW (Permit to Work), prior to allowing to work. Frequently training should be conducted by the site supervisor/foreman. A daily safety briefing should be conducted.
- Hot work permit
- Lifting Plan
- Confined space
- Working at heights / Working on scaffolding or MEWP (Mobile Elevating Work Platform) – Third-party certification for workers (competency certificates), operators, and equipment.
8. Definitions
MS – Method Statement
QCP – Quality Control Procedures
ITP – Inspection and Test Plan
ITA – Independent Testing Agency
IFC – Issued For Construction
LPG – Liquefied Petroleum Gas
NFPA – National Fire Protection Association
MEP – Mechanical, Electrical, Plumbing
STARRT -Safety Task Analysis Risk Reduction Talk
RAMS – Risk Assessment Method Statement
HSE – Health, Safety & Environment
BMS – Building Management System
Responsibilities
Project Manager
The project manager shall be responsible for overall project planning, procurement, technical submissions, and drawing submissions,
The project manager shall coordinate activities within the site team and with the management for the timely completion of activity in accordance with contract requirements.
Project Engineer
The site engineer is responsible to carry out the work as per approved shop drawings and method statements. He is also responsible to ensure adequate tool kits required for the works are in place prior to the starting of work. The site engineer reports to the Project Manager.
The site Engineer is responsible to ensure work has been done as per the specification and drawings; inspections are carried out based on ITP and quality control procedure and coordinate with QA/QC department for inspections.
The site engineer is responsible to ensure that all safety precautions are ensured in place and that all
personnel on-site are using the required personal protective equipment like helmets, gloves, shoes, and reflective jackets. The site engineer in coordination with safety officers will ensure all relevant permissions are taken prior to the commencement of works.
QA/QC Department
The QA /QC department will be responsible for overseeing the quality requirements and quality control measures for the project in coordination with the project engineer and project manager.
Safety Engineer
The SHE officer will be responsible for the safety, health, and environmental aspects on site as per the project safety and environmental requirements/safety standards in coordination with the project engineer and project manager.
Methodology
Site Preparation
The equipment tools and consumables required shall be planned and arranged at the site before commencing the installation.
Prior to mobilizing the equipment at the site, ensure that the areas are clear and no obstruction for the movement of the machine.
Safety barricades are available and installed in the areas where the equipment shall be working.
Coordinates of the site access shall be set out, marked, and protected.
The Project Engineer shall be responsible for the coordination and interfacing with other contractors during the installation works.
At the work front, if there is any interface with other contractors, they shall be informed well in advance and necessary precautions shall be taken care of.
Inspection requests will be submitted to the consultant for approval. Proceed if approved, rectify the works, and resubmit if not approved.
Implementation of Work
Tank area to be kept ready for plant and equipment before they arrive at the site. As soon as the plant and equipment arrived on-site, they will be erected with the required resources.
Welding will be carried out for piping as per the third-party approved WPS by Qualified welders with valid certificates.
Sufficient field joints in the pipe will be kept for adjustment alignment and modification if required. Once all installation activity is completed, remove all equipment connections and the complete piping system will be flushed by using nitrogen.
After completion of the flushing of all pipelines, all equipment will be connected.
After completion of all activities, a final inspection will be conducted and recorded.
Implementation of Work (Electrical)
Inspection of delivered materials and get approval from a consultant.
Conduiting with suitable size of GI conduits and trunking wherever applicable, putting junction boxes for easy cable pulling and zone separation according to approved drawings.
Cable pulling for gas detectors and panels after leaving some extra length for site variations.
Installation of supports for gas detectors and detection panels.
Glanding of cables with the proper size of cable glands, Meggering, and continuity test after installation.
Termination of cables inside gas detectors and gas detection panel as per technical recommendation from the manufacturer and approved drawings.
Connection of solenoid valves, sounder, and emergency push buttons.
Procedure for LPG Storage Tank Installation
Tanks will be positioned in the tank pit using the appropriate size of the crane and required accessories like a sling provided by the main contractor.
Dimensions and location of the tank pit should be as per the approved drawing.
After the tank has been positioned in the tank plinth, it will be backfilled using fine sand.
Procedure for piping hook-up to equipment
The completed piping will be hooked to the plant & equipment as soon as they are erected or if equipment arrival coincides with the construction schedule the piping will follow the completion of equipment installation.
Sufficient field joints in the pipe will be kept for adjustment alignment and modification if required.
All the nozzle location orientations will be checked for the installed pipes after the equipment is in position. If any modification is required to match the Equipment nozzle connection to the piping will be done.
All pipe connections will be checked for ensuring that it is connected without tension.
Once all installation activity will completely remove all equipment connections and the complete piping system will be flushed and pressure tested by using nitrogen.
Pipelines shall be connected to equipment after completion of installation and testing.
After completion of all activities, a final inspection will be conducted and recorded
Hangers and Supports Installation
A. Ground-Level Pipe Supporting:
The distances between each pipe support will be as per the approved drawing.
The support will be of the “C” channel.
One side of the channel will be bolted to the concrete slab/floor (existing slab/floor).
Another side will be used for pipe placement with a proper “U” clamp.
The “C” channel supports will be painted to avoid corrosion.
B. High-Level Pipe Supporting:
The distances between each pipe support will be as per the approved drawing.
Threaded Rod with rubber-lined clamp support will be used to hold the pipe.
One side of the threaded rod will be fixed to the ceiling with the help of a drop-in anchor.
Rubber clamp shall be installed as per the approved material submittal.
Install Hanger for horizontal piping with the following maximum spacing and minimum threaded rod size as per project specification;
DN 25 and smaller: maximum span 2438mm, minimum rod size 10 mm
DN 32: maximum span 2743mm, minimum rod size 10 mm
DN 40 and DN 50: maximum span 2743mm, minimum rod size 10 mm
DN 65 to DN 90: maximum span 3000mm, minimum rod size 13 mm
DN 100 and Larger: maximum span 3000mm, minimum rod size 16 mm
Pipe in Pipe Installation Procedure (C.S. Double Containment Pipe Installation)
Site-fabricated metal spacers as per the OD of the carrier pipe & suiting ID of the containment pipe are inserted at appropriate locations on the carrier pipe.
The containment pipe is then slid on the carrier pipe.
The unit is then raised to the installed pipe supports.
The carrier pipe is first welded followed by the containment pipe. Pressure test to be completed before containment pipe welding.
Wherever the containment fittings cannot be inserted into the pipe it is cut into split parts and welded.
This arrangement will be most applicable for tees, elbows, and reducers.
Welding Procedure
Before the commencement of any welding activity, the following works are required to be carried out;
The material to be used as an approved material submittal.
WPS approved by the third party.
Welding is done by welders qualified by the third party
The work area is clean and safe
A hot work permit has been obtained prior to starting the welding works.
Fabrication Procedure & Installation for Aboveground Piping
GTAW (Gas Metal Arc Welding) will be followed for carrier pipe welding and SMAW (Shielded Metal Arc Welding) will be done for Containment pipe welding.
Measure the length of pipe required, making due allowance for any pipe fitting to be used. Cut the pipe to the measured length ensuring that the ends are cut square.
Prepare the end of the pipe to the pipe to be welded to the right angle of level and the size of the ‘V’ bell and root face in accordance with procedure specifications. The surfaces to be welded shall be smooth, uniform, and free from laminations, tears, scale, slag, grease, paint, and other deleterious materials that might adversely affect the welding. Power tools or hand tools will be used for cleaning grinding or both.
The two prepared ends to be welded pipe to pipe or pipe to fitting shall be aligned as accurately as is practical and ensure that the spacing between the abutting ends is in accordance with the procedure specification used.
The alignment of the abutting ends shall minimize any offset between the surface caused by dimensional variation and will equally distribute around the circumference of the pipe any such offset. The hammering of the pipe to obtain a proper lineup will be kept to a minimum.
The two prepared ends shall be tack welded together in four positions at ninety degrees. After tacking, the alignment shall be checked to confirm the integrity of the alignment has been preserved during the welding process the tacks shall be removed by grinding.
The welding process will commence, ensuring that the correct filler metal, electrical current, polarity, voltage, amperage, and the number of passes are in accordance with the welding procedure. All slag of foreign metal shall be removed from each pass of welding, including the repair of any visible defects, such as cracks, cavities, etc. prior to commencing the succeeding passes. The removal of any such impurities will be done by electronic power tools such as grinders.
After the completion of the weld, the weld will be visually inspected to check for inadequate penetration, excessive undercutting, and burn-through and to ensure the weld is free from cracks. After inspection, any defects found are to be rectified.
A 10% radiography test will be conducted for the carbon steel carrier pipe butt weld joint.
Underground PE Piping Installation and Welding Procedure
Electrofusion Fittings contain electrical filament wires which, when correctly connected to an appropriate power source for the specified period of time, will fuse the coupling onto the pipe.
It is possible to join dissimilar polyethylene pipes and wall thicknesses by using electrofusion fittings. For example, PE80 fittings may be used to join PE100 pipe.
The tooling required for the welding of an electrofusion fitting is a suitable electrofusion control box with a power supply and a scraper capable of removing 0.2-0.4 mm from the outside of the polyethylene pipe.
An alignment clamp should be used to ensure that the joint’s movement is kept to a minimum during the heating and cooling cycle together, with cleaning cloths and an indelible pen. A welding shelter should also be used to provide protection of the welding area against adverse weather conditions and contamination.
Using cleaning cloths firstly clean the area of the pipe to be welded of any surface debris.
Without removing the sealed packaging marks on the pipe, the area which is to be scrapped, i.e. approximately 15-20mm beyond the insertion depth of the coupler.
Using a suitable pipe surface preparation tool “scraper” remove the pipe surface in the selected area to a depth of 0.2-0.4mm; it is imperative at this stage of the operation that this is performed correctly. Wherever possible a mechanical end preparation tool is the preferred method of pipe surface preparation as it is capable of removing a continuous, even layer from the pipe surface.
Do not touch the scraped surface.
Open one side of the sealed bag containing the electrofusion fitting and slide it onto the pipe.
The electrofusion coupler is fitted with a center stop. Slide the fitting along the pipe until it comes into contact with the center stop. Mark the insertion depth using an indelible marker pen.
Leave the bag over the end of the coupler to protect against contamination coming into contact with the inside of the fitting.
Scrape the second pipe as demonstrated above.
Remove the bag covering the coupler and insert the second pipe up to the center stop. Then mark the insertion depth using an indelible marker pen.
Correctly position and fit the restraining clamp to the assembly.
Clamps should always be used to secure an electrofusion assembly during the fusion cycle.
Having ensured the power supply is working correctly connect the electrofusion control box to the fitting and power supply.
Follow the instructions given on the fusion box’s display screen.
Input the fusion time either by using the information embossed on the coupler or by using the bar code affixed to the fitting. The method used will depend on the type of control box being used.
Once the coupler has completed the fusion cycle check that the melt indicators/melt wells show a successful fusion cycle has taken place. Melt wells, as shown above, should fill with melt to a point approximately flush with the surface of the fitting. The melt indicators fitted to predominantly smaller fittings will rise beyond the body of the electrofusion fitting.
The coupler must be left in retaining clamps for the full cooling time specified on the fitting although the terminal leads may be removed with care at the end of the fusion time.
Flushing procedure for LPG pipeline
Flushing of LPG pipes for the LPG system will be carried out to ensure that no sand, debris, and other foreign materials remain inside the pipeline before commissioning/testing the LPG system.
The following steps will be followed for flushing the LPG pipeline.
Remove/Disconnect all instruments like the pressure gauge before starting the flushing operation.
Avoid sand, debris, and other foreign particle transfer to the pressure regulator, by closing isolation valves provided in the suction and discharge side of the regulator.
Nitrogen will be used to flush the LPG pipeline.
The pipeline will be pressurized to min 1 bar pressure for flushing operation.
By maintaining the same pressure, open vent valves at the opposite end of the line to remove the foreign particle from the pipeline.
After completion of flushing of the LPG line, the complete line will be pressure tested.
Pressure Testing of LPG Pipeline
Check the system for proper installation in accordance with the relative drawing and design specifications.
A calibrated pressure gauge to read not less than 1.5 times the testing pressure will be used.
The LPG pipeline shall be pressure tested with a nitrogen cylinder. A calibrated pressure gauge will be used for measuring and monitoring the pressure in the line during testing.
Start the test by raising the pressure incrementally step by step.
Wait for 10 minutes for pressure equalization.
Increase the pressure in 1 bar increments till the system under test attains the test pressure.
For each test level, the pressure will be held for 5 to 10 minutes prior to allowing the authorized test personnel to approach the system for a soap bubble leak check at the weld, threaded, and flange joints.
Any repairs other than the tightening of nuts require depressurization.
Once the pressure has been attained, allow the pressure to hold for 2 hours. If the pressure has not fallen the nitrogen gas shall be slowly released to the atmosphere through a gauge manifold. Pressure testing will be offered to the client/consultant for inspection and approval. The entire pressure testing will be documented for the record.
The documentation of the pressure testing to be approved by the client/representative will be kept in the records.
For LPG vapor line pressure was tested at 6 bar, and liquid line pressure was tested at 20 bar. LPG storage tank pressure was tested at 9 bar during the authority’s final inspection.
Surface Preparation & Painting
The pipes will be cleaned using a cotton cloth to remove all dirt, grease, and other foreign material present on them.
Primer will be applied on the surface of the pipe which will be considered as an initial coating of paint.
Paint will be applied as a final finish which will be done by using a hand brush or roller to get uniform thickness.
The painting brush will be replaced at regular intervals.
The LPG carrier pipe will be painted with 2 coats of primer.
The LPG containment pipe will be painted with 2 coats of primer and 1 coat of topcoat. The final finishing of the paint will be done for the LPG line with golden yellow as per requirement.
The LPG liquid line will be painted with white color as per requirement.
Tagging, Labeling, and Identification
Provide proper tag numbers for the equipment nameplates & tags with the manufacturer’s product name.
LPG pipeline will be marked by the approved type of Identification labels with the specification and arrow mark.
Use numbers, letters, and terms indicated for proper identification, operation, and maintenance of mechanical systems and equipment.
Testing and Commissioning
Testing and commissioning of Gas Detection System
Check all the cable connections in the control panel for earth leakage by using a multimeter.
Switch on the control panel and wait for the panel warm-up time.
Configure the alarm setup to meet the cause and effect as approved shop drawing.
Verify that no error is displayed in the panel display.
Calibrate each detector using calibration gas and make the calibration report.
Energizing the gas detection panel and pre-commissioning of the system as follows:
Make sure the power supply is available in all the related areas.
Pre-commissioning and calibration reports are available.
The panel schedule is placed near the panel.
Integration with fire alarm/BMS system in coordination with fire alarm/BMS contractor according to approved cause & effect chart. Cabling will be done by the fire alarm/BMS contractor for this interface.
Apply the test gas to each detector and verify the cause and effect (sounder activation, solenoid valve operation, etc.)
Press and release the emergency push button and verify the solenoid valve operation.
Apply the test gas to detectors and verify the interface with the fire alarm (Gas leak signal needs to transfer from the gas detection panel to Fire Alarm Control Panel (FACP)).
Activate the fire alarm and verify the LPG main solenoid valve is closed during the fire alarm condition.
Document the test result.
Final testing, commissioning inspection, and approval from consultant/client.
Filling LPG in the System / Commissioning
The installation will be offered for the final inspection. Inspection comments are to be forwarded for review.
All comments are to be rectified, and re-inspected and final approval is to be forwarded to the client/consultant, prior to commissioning. Any comments on the integrity and routing of the piping system which require the dismantling of the piping or system shall require flushing, pretesting, testing to repeat, and subsequent approvals. Upon satisfaction, they will provide LPG for the particular installation before commissioning provided authority approval for the building to operate.
Before starting the commissioning, a safety permit shall be obtained from concerned parties, and commissioning is to be witnessed by the client/consultant.
For the first time filling, remove nitrogen from the system if thereby opening the vent valves in the vapor line.
Check pressure gauge readings for zero in LPG tanks and in the pipeline.
Switch on the power supply to the gas detection control panel and check the health status in all zones in the control panel.
Park the road tanker at the designated unloading area.
Apply the parking brake to avoid the movement of the road tanker.
Keep the road barriers on both sides of the road tanker with NO ENTRY signboards.
Connect the earthing clamp to avoid static electricity.
Make sure all Liquid inlets and vapor outlet valves in the liquid and vapor line for the tanks are closed.
Connect the road tanker hose to the correspondent inlet nozzle.
Slowly and partially open the liquid valve of the road tanker and allow LPG to fill inside the hose.
Note down the Road tanker level gauge/meter reading before the unloading operation.
Note down the LPG storage tank level gauge reading before the unloading operation.
Open the liquid inlet valves of the tank.
Open the tanker Liquid valves fully.
The liquid filling line will be flooded with LPG liquid, flowing into the tank from the road tanker.
The level of liquid LPG in storage tanks starts increasing, while road tankers start decreasing.
When the level gauge starts showing the level in the storage tanks this confirms LPG received in tanks.
After reaching the desired volume, close the valves in a liquid inlet.
Note down road tanker level gauge reading after unloading operation. Note down the LPG storage tank level gauge reading after the unloading operation
Close all valves on the road tanker.
Disconnect the hoses and earthling clamp.
Remove barriers on both sides of the road tanker and allow the road tanker to move from its place.
Open the vapor outlet valve on the tank which will be the inlet to 1st stage regulator.
Open the liquid outlet valve on the tank to the vaporizer. Open the vaporizer outlet valve which is connected to the regulator. The regulator set pressure is approx. 0.5 bar then it is connected to the vapor mainline.
The regulator outlet pressure is to be checked to be approx. 0.5 bar.
Finally, open the corresponding isolation valve to allow gas supply to the gas box and from the gas box to kitchen appliances.
Kitchen equipment commissioning is to be done by the Kitchen supplier/representative.
The scope of LPG commissioning to kitchen equipment will be activating the gas supply by opening individual gas box isolation to the solenoid valve.
Now gas flows to the piping up to the individual regulator inlets.
Open the isolation valve at the regulator inlet and light up the kitchen equipment to see a flame.
Fine-tune the equipment flames as required (to be done by the kitchen equipment supplier).
Manpower
Project Manager
Project In-charge
Electrical Engineer
QA/QC Engineer
Safety Officer
Foreman/Supervisor
Welder
Pipefitter
Firewatcher
Electrician
Semi-skilled workers/Helpers
Material
LPG storage tank
Vaporizer
Oil demister
LPG regulators
Ball valves
Seamless pipes and fittings
PE pipes and fittings
Gas Control Panel with detector
Emergency push button, sounder, etc.
Electrical cabling & conduits
Note: All materials shall be as per approved material submittal and all installation works shall be as per the approved drawings.
Equipment
Welding machine set with accessories
Wire brush
Chisel hammer
Buffing wheel
Hand grinding machine
Drilling machine
Hand tools, electric drill
Spirit level, measuring tape, tri-square, etc.
Calibrated pressure gauge
Other applicable tools & equipment
QC Approval
Follow the approved Method Statement, ITP, QCP, HSE Plan, Material Approval & Checklist.
Attachments
Risk Assessment
Inspection & Test Plan
Quality Control CheckLists
Welding Procedure Specification and Third-Party Approved Welder Certificate
tag: method statement for LPG
