Underground Piping Installation Procedure

This procedure is intended to provide general application guidance and establish controls during preparation and installation. To ensure that installation of underground cooling water line 60”diameter and smaller is carried out safely, efficiently and in accordance with good working practice, as per OWNER Job Specifications.

A. Required Tools and Equipment:

• 40-Ton Crane
• Welding machine
• Non-metallic ropes, tag lines 
• Shackles
• Welding gloves
• Welding mask
• Face shields
• Grinding machines / disc

B. Pre-Installation Activities:

• Ensure that all relevant documents have been approved by OWNER prior to commencing installation, and that the latest revisions of IFC drawings, specifications including approved procedures are disseminated to concerned personnel who will carry out the work.

• Ensure that all piping materials to be transported from warehouse / laydown area to the work area complies with the project specifications. Site handling and identification of all piping materials and components shall be in accordance with SUBCON Standard Project Instruction.

• Check and verify spool and random pipe installation location and co-ordinate with rigging section. Check pipes and spools materials if damaged or if end cover is in place before transporting to the work area. All materials of doubtful condition or quality shall be immediately segregated from the job site, an NCR raised and the material shall not be used.

• During transportation, spools shall be adequately secured with soft lines to prevent damage. Where practicable, end cap/protectors shall be installed to prevent ingress of any foreign objects and damage to weld preps.

• Over hanging from the trailer / truck body of any piping materials is not allowed. Ensure that they are properly and adequately secured.

• To prevent damages on coated pipe spools, handling shall be carried out with non-metallic slings. Chains or wire ropes shall not be used. Coated spools shall be stored on soft standing wood dunnage or sandbags. Attach soft tag lines, where necessary, to prevent swinging and possible damage during loading and handling of coated pipe spools.

• Check and verify the location and orientation of spools to plant North on IFC isometrics / plan drawings. Establish good reference points for proper alignment and commence installation in progressive manner.

• Starting from the North toward South of the plant, excavation using Dozer shall be carried out in accordance with SUBCON Standard Operating Instructions, ensuring that trench construction conforms to OWNER project requirements and specifications. Once the trench has been prepared and sand bedding brought to required grade and compacted, pipe installation may commence. Sand bedding shall be free of rocks, stones and other objects, which could cause damage to the pipe coating.

• Prior to setting the pipe on sandbags into the ditch, the underside of the cooling water line shall be holiday tested. Following coating of the welds and coating repair areas, the coating all around the pipe shall be tested to ensure there are no holidays. Holiday testing should occur just prior to authorizing the backfill activity. Backfill should begin within the next 8 to 24 hours. 

C. Installation Activities:

• Use a 40-ton Crane for installing the underground cooling water line. Non- metallic ropes and tag lines shall be attached to the pipe for controlling and to prevent swaying and damage to coating during lifting and installation. The pipe will be lifted and positioned horizontally (see attached drawing) and will be lowered into the trench in accordance with SUBCON Standard Operating Instructions.

• The pipe spool will be placed on a pile of sandbags in the trench with adequate access around the full section of the joint to be welded by excavating enough depth from the graded bottom at the weld area location. Provide sufficient support to the pipe section in the trench to prevent movement / misalignment.

• Conduct dimensional check, verify the squareness of the pipe end at the weld bevel and grind if required, to ensure the joint can be accurately fitted and aligned to obtain good weld quality.

• Proceed to lower the 2nd pipe spool into the trench and maneuver into a position level with the pipe string already in place. Do not force fit any pipe joint during fit-up, this will minimise stress exerted on the pipe. External clamps and other similar devices shall be used to retain/maintain the pipe position and alignment during tack welding.

• Only a qualified welder shall carry out tack welding in accordance with Procedure No. QCD-####. Submit “Fit-up” request (WIR) for each pipe joint and on acceptance of fit-up assign a welder. Only approved welding electrodes / filler rods shall be used and controlled in accordance with SUBCON Q.C. Procedure No. QCD-#### and the approved Welding Procedure Specifications (WPS).

• Once fit-up is accepted, ensure that weld area is clean, free of dirt, scale, rust paint, or any foreign objects and ensure adequate protection from wind, dust, rain, and wind blown sand before full welding shall be carried out.

• Welding shall not be done when the ambient temperature is lower than 0ºF (-18ºC) or when surfaces are wet, exposed to rain, sleet, or high wind.

• Accomplish welding in one complete heating cycle (where possible), balancing the deposition of the weld metal to minimise distortion resulting from the effects of heat input. No weld joint should be left until, Root, Hot pass and one substantial filler has been completed.

• Prior to welding inspection, clean all welds using grinder and or wire brush. All welding inspection shall be in accordance with OWNER Specifications No. W01-F01 and SUBCON Standard Operating Instructions respectively. Non-destructive examination shall be carried out in accordance with Specification No. 00-W-0003. Any repair on welding shall be done in accordance with SUBCON Q.C. Procedure No. QCD-####.

• If flange joints are to be connected, all bolting requirements shall be carried out in accordance with OWNER Specification and SUBCON Work Instruction No. PRJ-####.

• At the end of each workshift, the open ends of the installed pipe shall be secured / covered using frame supported polyethylene / tarpaulin sheets to prevent ingress of any foreign objects or living organisms.

• The same methodology shall be applied for the installation of the next succeeding pipe until the last pipe spool is fully installed to complete the system.

D. Post-Installation Activities:

• Upon completion of welding inspection and acceptance of OWNER, repair for any damaged coating shall be carried out in accordance with coating material manufacturer’s recommendation, SUBCON Standard Operating Instructions and project Specification No. 00-N-0031.

• After obtaining NDT clearance from quality control, all field joints shall be coated with coal tar epoxy coating in accordance with SUBCON work instruction / method statement.

• Prior to backfilling and compaction works, all waste materials and sharp objects shall be removed from the trench. Extreme care shall be observed when placing backfill materials to avoid damage to pipe coating. Backfilling and compaction shall be carried out in accordance with SUBCON Standard Operating Instructions.

• The sand bedding material shall be dune sand meeting the requirements of Procedure No. 81-C-0001, Rev. 1 “Method Statement Procedure of Backfill for Cooling Water Pipes”.

• Structural fill material shall meet the requirements of 00-C-0010, “Specification for Excavation and Backfill”. 

• For final backfill, compaction of the dune sand surrounding the pipe may be achieved by using water flooding. Dune sand to be compacted by water flooding should be placed in lifts not exceeding 200mm. Mechanical compaction in the area directly above the pipe should not begin until there is a minimum cover of 300mm (loose lift thickness) of dune sand above the pipe.

• Conduct housekeeping properly.

Would you like to take the full version, including its native file, of the Underground Piping Line Installatin Procedure Template?  

The full version includes the following;

I. Purpose
II. Scope
III. References
IV. Responsibilities
V. Work Sequence & Procedue {as described above}
VI. Inspection & Quality Records
VII. Safety Precautions

Then, simply click the "DOWNLOAD Now" below;