Method Statement for HDPE Pipe Installation

method statement for HDPE pipe

I. Description of Works

The method statement for HDPE installation defines the steps to be followed in order to ensure that pipeline
welding, laying, and associated works are performed as per project specifications, HSE, and quality requirements.

Definitions

QC-Quality Control
HSE-Health, Safety & Environmental
CEMP-Construction Environmental Management Plan
HDPE-High-Density Poly Ethylene
GPS-Global Positioning System

References

HSE Plan
CEMP
General Lifting Plan,
HDPE Pipe Material Submittal
DVS 2202, Technical Codes on Plastics Joining Technologies
DVS 2202 – 1, Imperfections in the Thermoplastic Welded Joints
DVS 2203 – 1, Testing of Welded Joints of Thermoplastic Sheets and Pipes-Test Method Requirements
DVS 2203 – 5, Testing of Welded Joints of Thermoplastic Plates and Tubes-Technological Bend Test
DVS 2207 – 1, Welding of Thermoplastics- Heated Tool Welding of Pipes, Pipeline Components and Sheets Made HDPE
DVS 2208 – 1, Welding of Thermoplastics- Machine and Devices for the Heated Tool Welding of Pipes, Piping Parts, and Panels
ASTM 2557 – Thermal Butt Fusion Welding Procedures
DIN 8074 & DIN 8075 – HDPE Pipes for Clean Water
ISO 4427 – 1996: Polyethylene Pipes for Water Supply-Specifications
ISO 11414 – 1996: Plastic Pipes and Fittings-Preparation of PE Pipe Assemblies by Butt Fusion
Shop Drawings
Project Specifications
Method Statement for Surveying Works
Method Statement for Excavation & Backfilling
Method Statement for Cast In-situ Concreting
Method Statement for Dewatering System
Method Statement for Waterproofing

There are various DVS 2207 standards that deal with thermoplastic jointing. The first part of the standard discusses heated tool welding of PE-HD sheets, pipes, and pipeline components. In addition, this section covers heated plate butt welding, socket welding, and electro-fusion welding of pipes. In this standard, instructions for how to prepare components for welding, how to carry out welding itself, and how to test the welding are laid out.

DVS 2207

Responsibilities

Project Manager

Responsible for accomplishing the stated project objectives which include creating clear and attainable project objectives, building the project requirements, and managing the constraints of the project management triangle, which is cost, time, scope, and quality.

The Project Manager shall be responsible for ensuring that the Project Quality Plan and the Inspection and Testing procedures, Method Statement for HDPE Pipe Installation, HSE safety, and all contractual documentation are maintained up to date and accessible to all parties.

Construction Manager

Responsible for overall construction activities ensuring that all Method Statement for HDPE Pipe Installation , quality, and safety procedures are implemented and required approval permits are obtained.

Temporary Works Manager

To support the project delivery teams, to support and lead the management and delivery of temporary works engineering whilst ensuring program, cost, quality, and safety objectives are achieved.

Temporary Works Coordinator

Coordinate all temporary works activities on each specific area, ensuring that all temporary works are adequately and safely designed, constructed, and used.

Site Engineer

Supervise operations in accordance with the approved Method Statement for HDPE Pipe Installation, shop drawings, specifications, material submittals, and schedules to achieve the acceptance of the project deliverables.

HSE Manager

Health, safety, and environmental (HSE) managers generally plan, coordinate and implement issues and directives within the organization.
They ensure safe environmental working conditions for all employees.

HSE Engineer

Ensure enforcement of safety procedures in accordance with the approved HSE Plan.
Will be closely monitoring the site engineer’s strict implementation of the Method Statement for HDPE Pipe Installation 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.

II. Resources

Plant and Equipment

Drilling Machine
HDPE Butt Fusion and Welding Machine
Survey Equipment
Electrical generators, fusion coupler
Clamps, Jointing Tackles, trimmers & heater plate
Slings & Ropes
Cutting machine
Rollers
Spanners
Torque wrench
Ladder
Pipefitter Tools
Testing instruments & equipment such as pumps, gauges, stop ends, etc.
Barricade/Plastic barriers
Hydraulic Excavators
Mobile Crane as required for the lifting of materials
Rock Breaker (when required)
Jointing Tackles
Dewatering Systems
Water Tankers

Workforce

Site Engineer
HSE Engineer
Helper
Equipment Operators
Rigger
Banksman
Welders
Pipefitters

Light Tools

Hand tools as per site requirement for construction
Power tools as per site requirement for construction

III. Materials

Approved HDPE Pipes and fittings
Dune sand
Precast concrete blocks
Approved pipe bedding and surround material
Approved backfilling materials
Detectable warning tape
Concrete grade C20 as blinding, pipe bed and surround

IV. Site Planning

Duration of work shall be indeterminate but will not critically affect the progress of the project.

Preparation

Permits from the concerned authorities shall be obtained prior to start work at the site.

The contractor shall ensure that all gate passes, permits, tools, materials for safety precautions, manpower, and equipment are available before the commencement of work.

The site team shall make sure that access roads are always clear from any obstruction and the site is always accessible.

Site Clearance

The working area shall be cleared of all debris, materials, or other obstructions.

Traffic Management

The Site Team with the assistance of the Safety Officers shall coordinate logistics and materials movement through the area 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 for reference by authorized personnel.

Pre-construction Safety Meetings

The meeting shall be scheduled prior to the beginning of the work and before any Sub-contractor
starts on the project.

  • General contractual safety, health and environmental requirements.
  • Traffic safety will be discussed to emphasize these meetings.
  • Roles of the contractor, subcontractors, authority representatives and all project workers.
  • Accident reporting requirements.
  • Specific details of the work to be performed along with the use of personal protective
  • equipment.
  • Emergency procedure.

V. Methodology-HDPE Pipe Installation

V.1 Earthworks

The contractor will prepare and maintain the pipe installation area free from obstructions and other activities during the installation process.

V.2 Storage, Handling and Transportation

Handling and transportation of piping materials shall be done with utmost care to avoid any damage. The quality level of the materials should be maintained from delivery to the finished project. Damages of the surfaces (scratches, marks, etc.) have to be avoided. The storage has to be free from waste such as stones, screws, nails, etc.

  • Pipes and fittings shall be protected at storage against humidity and UV (Ultraviolent) radiations (especially polypropylene)
  • Pipes >630mm, a maximum of two rows may be stored on top of one another.
  • Pipes >1000mm shall be stored loosely and preferably in a vertical position.

All materials intended for installation shall be stored on suitable supports (timber, sandbags, pallets, etc.). No material shall be stored directly on the bare ground. Pipes have to be stored flat and without bending stress, if possible in a wooden frame. All open ends of the HDPE pipes & fittings shall be protected by end caps or covered to avoid dust and dirt collection inside the pipes.

Lifting tools (belts, shackles, chain blocks, etc.) for HDPE pipes and fittings shall be used in accordance with good engineering practice to lift with safety and great care and shall be inspected prior to work commencement.

The HDPE pipes and fittings must be securely tied to both sides and end with belts or ropes. While traveling the HDPE pipes should not vibrate and or slide on the trailer bed causing damages to the external surfaces.

All spooled parts shall be lifted and transported in a similar manner. Special care shall be taken to avoid any significant deformation or stress during lifting or transportation.

The target of the unloading operation shall be the minimum lifting and moving activities for the material. In this way, the damage of the parts/material will be reduced practically to none.

Prior to the installation of the HDPE pipes and fittings, the face of the pipes and fittings shall be cleaned.

All pipes and fittings shall be protected against damage during handling from supplier to fabrication yard and further to final installation at site. Special care shall be taken to seal surfaces of pipes & fitting ends, and avoid contact with other materials (e.g.: oil, grease, etc.) to avoid surface contamination.

This also includes protection during the erection phase in order to avoid contamination from other activities on the site.

Transportation of any material shall be arranged taking the following points into consideration:

  • HDPE pipes and fittings, item shape, dimensions, and weight
  • Transportation route
  • Workspace around the installation area
  • HDPE pipes and fittings installation sequence
  • Certified lifting equipment and tools.
  • Safety precautions.
  • Qualified personnel (Crane operators, Riggers, etc.)

V.3 Pre-fabrication of HDPE Pipes and Fittings

HDPE pipes and fittings shall be inspected for the sizes required and for distortion, bending, damages, etc. Each section of pipe and each fitting shall be thoroughly cleaned before it is installed.

When the work is stopped at the end of the day, the open ends of all pipes & fittings shall be closed.

Nylon slings shall be used is capable of safely carrying the load to lift, move, or lower pipe or fittings. Flange adapter and flange fittings shall be centered and aligned to the mating component before assembling and tightening bolts. Flange bolts shall not be used to draw the connection into alignment.

Bolt threads shall be lubricated and flat washers shall be used with nuts. All work shall be carried out by experienced and trained personnel on the joining of HDPE piping.

Butt Fusion Welding of HDPE Pipes
Butt Fusion Welding of HDPE Pipe

V.4 Butt Fusion Welding

Welding of pipes (Butt Welding) shall be in accordance with DVS 2207-1.

The butt welding method is the most commonly used method of joining HDPE pipes and fittings. No extra material is used instead the surface to be joined is heated by means of a heating plate.

The melted surfaces are then pressed together and will fuse into each other forming a strong joint. The strength of the material is based on the fusion of atoms.

Welding beads shall not be removed and are usually kept as a visual reference for the welding quality.

Welding machines have strong body frames, guide rods for the pipes, a pipe end planer, and an electric heater plate.

The compressive thrust is produced hydraulically or by means of a lever or spring mechanism. To achieve a good welding result it is better to use a proprietary machine.

Generally, the butt welding operation is divided into the following steps.

  • Create permissible working conditions.
  • Connect the welding device to the mains or to the alternating current generator and check its function.
  • Clean the joining faces beyond the welding area with a cleaning agent and unused, absorbent, non-dyed paper.
  • Align and scrape pipe ends with the planer.
  • Close the pipe ends against draughts.
  • Check the alignment.
  • Check the heating tool temperature.
  • Clean the heating tool with a cleaning agent.
  • Heat up surfaces to be welded.
  • At the end of the heating cycle, detach the joining faces to be welded from the heating tool and move the later out of welding position.
  • Drive the pipe ends together by applying the correct fusion pressure as indicated in the welding table, while monitoring the welding bead formation.
  • Unclamp the welded parts (pipes, fittings, etc.) when the cooling time has elapsed.
  • Inspect visually for any visible anomalies.

V.4.1 Measures before Welding

The welding area shall be protected from unfavorable weathering influences (e.g. wind, rain, high humidity levels, etc.). When working outdoors; the area used for joining shall be protected from rain, snow, and wind.

The preferred ambient working temperature for welding is in the range of +5°C to +45°C. If necessary, protecting the welding area with a tent or similar arrangement shall be arranged to maintain a constant environment in the working area.

V.4.2 Cleaning

The joining faces of the HDPE pipes, fittings, tools and the heating element must be clean and free from contaminations (oils, fats, grease, chipping, etc.).

The paper used for cleaning must be unused, absorbent, non-fraying, and undyed.

The heating element must be cleaned with paper before every welding operation. No residues of cleaning agent or paper shall remain on the heating element.

The pipe ends to be joined shall be scraped immediately before the beginning of the welding.

Any chips must be removed prior to welding of pipes.

V.4.3 Preparation for the Welding

The heating element temperature shall be checked before the start of the welding work. A high-speed thermometer shall be used to control the heating element temperature prior to each welding process.

Control measurement must happen within the area of the heating element which corresponds to the pipe surface. In order to achieve a thermal balance, the heating element should be used not before 10 minutes after reaching the required temperature.

For optimal welding, the heating element shall be cleaned with unused, absorbent, non-fraying, and undyed paper prior to the start of every welding process. The non-stick coating of the heating element must be undamaged in the working area.

In addition during the pipe welding process by slow movement of the workpieces occurs a movement pressure or movement power which can be seen on the indicator of the welding machine and should be added to the first determined joining power of joining pressure.

The nominal wall thickness of the parts to be welded must correspond to the joining area. Before clamping the pipes and fittings in the welding machine they must be aligned axially.

The areas to be welded should be cleaned immediately before the welding process with a clean, fat-free planner tool so that surfaces are aligned in the clamped position. The following table provides the permissible gap widths under adapting pressure:

Pipe diameter, d (mm) Permissible gap width (mm)
≤355 ≤0.5
400 <630 ≤1.0
630 <800 ≤1.3
800 <1000≤1.5
1000 ≤2.0

Together with the control of the gap width, any misalignment of pipes should also be checked.
The misalignment of the joining areas to one another should not overstep the permissible degree of 0.1 x wall thickness on the pipe outside or on the table respectively.
Prepared and cleaned welding surfaces shall not be left open for an extended time, nor shall they be touched by hands otherwise a renewed preparation (cleaning, scraping, etc.) is necessary.

V.4.4 Welding of HDPE Pipes and Fittings

  • Place the machine on even, horizontal, and dry ground.
  • Check that the right sizes of clamps are fitted into the machine.
  • Place the supports line up by eye.
  • Pull the pipe into fixed clamp, longer pipes always should be on the fixed pipe clamp side.
  • The pipe end should be 50mm outside of the pipe clamp to allow trimming and heating.
  • Adjust supports to ensure the pipe is in line both vertically and horizontally with the machine.
  • Lift upper pipe clamp onto the machine. Screw-on pipe clamp nuts. Upper bolts protrude through holes in the upper pipe clamp, bottom then aligns automatically.
  • Tighten the pipe clamps nuts by hand or socket spanner.
  • Load shorter pipe into movable pipe clamp side. The pipe must be aligned so that when ends are not straight, they initially are loaded into the machine point to facilitate straight trimming.
  • Check the position of the movable pipe clamp. The clamp should be in a fully open.
  • position to allow proper heating and welding, if the clamp is in a closed or nearly closed position the moving range of the clamp (hydraulic cylinders) is not enough and the forces during welding will load the body frame of the machine only.
  • Adjust supports to ensure the pipe is in line both vertically and horizontally with the machine.
  • Tighten pipe clamp nuts. Pipe clamp nuts should be tightened to give coarse alignment of pipe ends. Bottom nuts will move pipe end up. Top nuts will move pipe end down.
  • Adjust pipe ends for fine alignment with the centering blocks.

V.4.5 Trimming of Pipe Ends

  • Clean planer disc on both sides.
  • Clean pipe ends of each pipe (20mm) using lint-free cloth and fluid (Ethanol).
  • Align gear in the center of the gap.
  • Place planer into the machine. Ensure planer is the incorrect rotating direction to cut.
  • Lock planer into place with planer holder.
  • Start the planer motor.
  • Move movable pipe clamp until it touches the planer’s face.
  • Trim the pipe ends (Safety measures while trimming are included in the health and safety section).
  • Allow hydraulic pressure to fall to “0” zero. Planer will be rotating freely.
  • Open hydraulic valve.
  • Open the machine.
  • Turn off the planer motor.
  • Remove the planer.
  • Remove cuttings from pipe ends. Only use a cloth to remove cuttings from inside the pipes.
  • Close machine and check alignment of end faces.
  • Repeat trimming if pipes faces are not properly aligned face to face.
  • Close movable pipe clamp side.
  • Note and record friction force (also called “drag force”).

V.4.6 Temperature Setting


The butt fusion welding process requires the pipe surfaces to be joined, to be warmed up to the required welding temperature by means of a heating element prior to them being joined together under pressure. The heating element temperatures are listed in the following table.

Generally, the aim is to use higher temperatures for smaller wall thicknesses and lower temperatures for larger wall thicknesses.

PE PPPVDFECTFE
Heating Element
Temperature (Degrees C)
200 up to 220200 up to 220232 up to 248275 up to 285
PE-(Polyehylene), PP- (polypropylene), PVDF-(Polyvinylidene fluoride),ECTFE-(Ethylenechlorotrifluorethylene)

Heat the plate to the required temperature range of 200-220 °C.

Check the temperature and the spread of temperature over the entire heater plate by means of a surface thermometer. Variation of the temperature over the surface should not be more than 10 °C from the set value.

V.4.7 Heating of Pipe Ends

  • Clean the heater plate surface using a cleaning agent which should be a 100% vaporizable solvent.
  • Place the heater plate into the machine between the pipe surfaces to be welded.
  • Move the movable pipe clamp side until trimmed pipe ends touch the heater plate.
  • Close the hydraulic valve and apply heating pressure.
  • Attach heater plate chains (if applicable) in order to separate pipe ends from the heater plate and allow removal of the heater plate.
  • Observe the formation of beads against the heater plate. The bead should be uniform around the whole circumference of the pipe. The bead should normally be formed in a few minutes depending upon the diameter and wall thickness of the pipe. If major deviation occur, recheck welding conditions and start again.
  • When the bead has been formed, reduce the hydraulic pressure (P1) to maintain the pressure (P0) through the post heating period (t2) to allow deep plasticizing of pipe wall. If the heating time is too short, the molten material may be totally squeezed out when pipe ends are pressed together and fusion takes place between un-plasticized cold surfaces.
  • Open the movable pipe clamp so that pipes ends are clearly separated from the heater plate.
  • Remove the heater plate. Do not pull the plate along the pipe ends or twist it because the plasticized area may be distorted. Check both pipe ends by eye for bead damage. The removal time of heater plate shall be minimized as specified in welding parameters cycle (t3).
  • Close the movable pipe clamps by means of the hand lever.
  • Close the hydraulic valve and apply the welding pressure (t4). Increase the pressure gradually to the required pressure (P1).
  • Observe the size and the shape of the formed welding bead, which should be even on the entire circumference of the pipe.

V.4.8 Cooling of Pipes

Maintain the pressure throughout the cooling period (t5). Cooling should not be accelerated for instance by water or air. Proper cooling time as per welding parameters under pressure must be ensured to create a strong joint.

V.4.9 Removal of Pipes

  • Open all centering blocks, dismantle fastener if welding a stub end.
  • Check that hydraulic pressure is fully released.
  • Open the pipe clamps and remove the upper sections from the machine.

V.4.10 Flange Joints

The construction length of the neck must be taken into consideration when welding necks are joined to the pipe using the butt welding process.

For short welding necks that do not have sufficiently long cylindrical ends for clamping, welding machines with a neck holder must be used, if possible. In particular, this applies whenever, due to constraints, the loose flange has to be pushed over the neck before welding.

When integral flanges are to be welded, it must be ensured that the bolt holes are arranged symmetrically to both main axes of the pipe.

When installing butterfly valves in thick-walled thermoplastics pipe system, it must be ensured that the valve disc can be opened totally without hitting the inside surface of the pipe.

If possible, butterfly valves that are adapted to plastic pipes and whose valve disc is adjusted to the reduced inside diameter of the pipe should be used.

Loose flange, welding neck, integral flange, seal, and the loose flange shall be aligned centrally with the pipe axis. When aligning the seal, it must be checked whether the seal dimensions conform to the outside and inside diameters of the welding neck.

Before the bolts are tightened, gasket faces of the welding neck, neck bush, or the integral flange must be located parallel to one another and must be in close contact with the seal.

V.5 Joint Numbering and Report

After completing a welded joint, a unique number shall be given for traceability and recording purposes. The given number shall be clearly visible and must be written adjacent to the welded joint. This number shall allow the tracing of the welder name and the date of the weld on the welding log sheet.

The welding log sheet is prepared by the qualified welder and checked by the responsible QC Engineer and/or Project Engineer.

V.6 Inspection of Pipes, Fittings, and Joints

Welding is inspected visually for the size and evenness of the bead as well as the matching of pipe ends to each other.

Welding inspection is done as per DVS 2202 standard.

  • No bubbles or pores in the welding joint are allowed.
  • Joint number is noted and recorded.
  • Inspection is visual and based on the respective size and shape of the pipe / fitting bead.
  • V groove depth of bead is also noted.
  • Other methods applied are destructive material testing methods involving bending and tensile tests of sample pieces cut from the weld area of the pipe. Destructive test will be done on dummy joint on site and as specified under the welding principles.
  • Visually unacceptable joints should be cut out and re-welded using the correct procedure.
  • All parameters shall be maintained as per standard welding tables.
  • All actual welding parameters shall be recorded in the weld log sheet.
  • Welding specialist shall follow and record the welding parameters for each joint.
  • Sample weld tests by a qualified third party testing laboratory may be provided upon request.

Acceptance levels for welds made by butt welding shall be in accordance with DVS 2202-1 7.3 Table.

V.7 Welding Principle

The principle of butt-fusion welding consists of heating two surfaces to the designated temperature and fusing them by applying a sufficient force. The applied force causes the melted materials to flow and mix thereby resulting in a strong fusion.

When fused in accordance with the proper welding procedures, the joint area is expected to become as strong as, or even stronger than the pipe itself in both tensile and pressure properties.

As soon as the joints cool to near ambient temperature, the welded pipes can be handled safely.

V.7.1 Butt Fusion Welding Parameters

The reference values for heating element butt welding of HDPE, PP, PVDF, and ECTFE pipes and fittings are given at outside temperatures of about 20°C and low airspeed rate.

V.7.2 Specific Heating Pressure

In most cases, the heating pressure (bar) or the heating force (N) which has to be adjusted, may be taken from the tables on the welding machines.

For checking purposes or if the table with pressure data are missing, the required heating pressure has to be calculated according to the following formula:

When using hydraulic equipment, the calculated welding force (N) has to be converted into the necessary adjustable hydraulic pressure.

Calculation of the welding area:

Calculation of the welding force:

V.7.3 Alignment

In order to achieve a perfect alignment, the surfaces to be joined are pressed on the heating element until the entire area is flat and parallel to the heating element. This can be checked by the development of beads.

The alignment is finished when the bead height has reached the requested values on the entire pipe circumference.

The bead height indicates that the joining areas are entirely touching the heating element. Before the welding process of pipes with a larger diameter (>630mm), sufficient bead development also on the inside of the pipe must be checked.

V.7.4 Pre-Heating

During the pre-heating process, the surfaces to be welded must touch the heating element with low pressure. The pressure will fall nearly to zero (<0.01 N/mm²) once the material is molten.

Pre-heating is crucial to warm the required areas of the parts to be welded.

V.7.5 Adjustment

Once preheating is complete, the pipe surfaces shall be separated from the heating element.

The heating element must be removed promptly and without damaging the molten material.

The pipe surfaces must then be brought together quickly and the welding pressure shall be reached to ensure that the plasticized material is still hot.

The quality of the welding seam is influenced by the temperature of the plasticized material. A cold joint will have a negative influence on the long-term performance of the pipe.

V.7.6 Clamping Device

In order to avoid stresses in the pipe and potential deformations, the clamping devices should surround the pipe casing as parallel as possible to the welding plane. The geometric circular shape of the pipes shall be maintained and ovality shall be avoided.

Pipes shall be clamped tightly to avoid movement or sliding of the pipes even under the highest working forces. For fittings, such as stub flanges and welding neck flanges, special clamping devices which prevent deformation of the workpiece have to be used.

The pipe clamped at the movable side of the machine has eventually to be supported and exactly adjusted by means of easy-running dollies so that the working pressures and conditions required for welding can be maintained. If possible, the use of clamp elements adjustable in height is recommended to allow for better centering of the workpieces.

V.8 Weld Qualification

Visual inspection should be conducted for qualifying the welding and weld joints by a qualified third-party inspector as per DVS 2202 Standard.

V.9 Conducting Survey and Laying Out the HDPE Pipes

The area will be marked in a grid system after the baseline ground level is completed using a GPS system. All underground as well as existing services and obstructions are carefully identified and dealt with before this work begins.

The surveyor must ensure that all survey equipment has a valid calibration certificate, as well as that pipe laying is completed to the required line and level.

Other relevant data should be included in addition to the survey report.

The entire construction site’s original ground level will be surveyed and recorded. The data collected will be printed in hard copies for joint signature after the daily joint survey is completed.

Work will only begin in the surveyed area where the survey report is fully signed. 

A plan will be developed and submitted for approval after the full survey record is established.

Existing services must be identified using cable detectors and trial excavation, and they must be appropriately marked on the job site.

V.10 Trench for Pipes

In general, the trench width should be the minimum size that permits for safe operation and effective pipe laying, jointing, and bedding.

All pipes must have a cover height of at least 1200 mm measured from the top of the pipe to the final grade level or as specified in the approved drawing.

Where trenches are required to be deeper than the general depth mentioned the trench shall be dug to a required depth with a gradual slope necessary for the proper laying of the pipeline.

The trench width depends on the nature of the ground, depth, and pipe sizes. The clear width of the trench at any level shall be a minimum of one pipe diameter plus 300mm (±50mm).

The pipeline shall not be closer than 300mm to the other pipeline services or structures.

In all cases, the trench shall be excavated sufficiently to ensure efficient laying and jointing of pipes.

V.11 HDPE Pipe Bedding and Surround Material

Pipe bedding and surround material for HDPE Pipes shall be as per project specification.

All bedding and surround material shall be approved prior to use.

Pipe surround material shall be wetted and lightly tamped or compacted in place.

V.12 Pipe Laying

All pipes shall be laid in trenches at the required depth below the surface depending on the approved shop drawing and road details.

Pipes crossing the roads shall be protected fully and embedded in the sand.

All pipes fitting valves etc. shall be carefully lowered into the trench with suitable equipment in a manner that will prevent damage.

When work is not in progress, the open ends of the laid pipeline shall be securely plugged.

Install all pipes and fittings in accordance with the manufacturer’s recommendation, fixing each item firmly in position, level, plumb, and properly joined.

If necessary, special foundations or other fixing supports/blocks must be provided.

To prevent the pipeline from floating, the backfill must be sufficient to prevent the pipe from being exposed to foreign objects.

Any pipe that has floated must be removed from the trench and reinstalled in a dry trench.

After the various system components have been installed, all of the equipment and surrounding areas should be adequately cleaned before final closing. Any foreign material that is still on the equipment and in the surrounding areas should be removed.

V.13 Testing

Hydro-testing procedures for HDPE piping:

  • Ensure proper backfilling of the testing pipe, keep the joints open for inspection, and fill, pressurize, and test the section within the schedule time. One end of the test section should be closed with an endcap or blind flange, and the other ends of the test section to be connected with the testing flange having water inlet connected to the calibrated pressure gauge & air out let.
  • The test section should be filled slowly with water and ensure that no air is trapped in the section. The air release valve should be connected at the highest point of the system to expel any trapped air and to ensure that the system is completely filled with water.
  • Gradually increase the pressure in the test section to the required test pressure.
  • Maintain maximum test pressure by adding make-up water as needed.
  • Keep track of the test section during the test period.
  • As per ISO standard, a test at 15 times the rated pressure can be conducted at 20°C for 2 hours.

V.14 Construction of Appurtenances

The pipeline installation will progress as thrust blocks, valves, valve chambers, wash-out chambers, etc., are constructed based on approved shop drawings.

V.15 Construction of Piping within the pump house and valve rooms

Pipes will be connected with flanged joints as per the approved shop drawings and shall be hydrostatically tested at the pressure specified.

To ensure proper maintenance of flanges, the flange gasket must be centrally located, and the flange bolts must be tightened as per the manufacturer’s specifications.

Torque wrenches are recommended for securing the required compression. In accordance with the approved shop drawings, the proper supports should be installed taking into account their elevation and location.

It is recommended that torque be set according to the manufacturer’s recommendations.

VI. Risk Assessment

Please refer to the attached document in Appendix B.

VII. Permit and Licensing Requirements

Refer to Appendix C for Permit to Work.

VIII. Drawings, Diagrams, Maps, and Survey Data

Please refer to Appendix A.

IX. Pre-Start Safety Briefing Arrangements

Refer to Risk Assessment on Appendix B.

  1. Protective and Safety Equipment
    All workers involved shall be equipped with adequate PPE as stated below:
    a. Safety Helmet with Company Logo
    b. Safety Boots
    c. High Visibility Vest
    d. Safety Goggles
    e. Welding Gloves
    f. Coveralls
  2. Information to Personnel
    a. Safety Induction
    b. Job training
    c. Notices/Memos
    d. Toolbox talks
    e. STARRT Card
  3. Special Safety Requirements
    a. All necessary personal/protective equipment (PPE) as well as harness be provided.
    b. Banksman, wearing distinctive vests, shall be assigned to help operators maneuver their equipment.
    c. The equipment operators shall possess the required licenses and certificates.
    d. Generated dust shall be controlled by water spraying.
    e. 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.
    f. All working activity shall comply with Client Safety Procedure.
    g. First aid material.
    h. General management of protection/operation hazards are to be observed.

X. Environment and Quality Issues

Precautionary Measure
All precautionary measures shall be briefed to all workers prior to commence the activity.

Disposal Requirements
All waste shall be disposed of as per Construction Environmental Management Plan and as per government-approved disposal areas.

Inspection, Test, and Sampling
Request for Inspection and Testing will be submitted prior to and after execution of works.

MIR – Material Inspection Request
WIR – Work Inspection Request

XI. Quality Assurance Requirements

Refer to Project Quality Plan
a. Project Specifications

XII. Attachments-Method Statement for HDPE Pipe Installation

Appendix A:

  1. Butt Fusion Welding Parameters
  2. Shop Drawings
    Appendix B: Risk Assessment
    Appendix C: Permit to Work
    Appendix D: Inspection and Test Plan
    Appendix E: Welder Qualification
HDPE Pipe Installation

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