Work Methodology for Installation of Service Water Piping under ground
NOTE: Method of statement for excavation shall conform to MS for backfilling and compaction.
• All documents relevant to this particular section of work shall be check prior to installation.
• Check the areas if ready for the installation and free from any debris and unsafe condition.
• Ensure that the pipes and pipe fittings to be installed are clean and free of debris and foreign materials and suitable for installations.
Sequence of Work
Works will be performed in the following sequence:
• Coordination of work with other departments including civil, mechanical and safety.
• Shifting of required materials to work place.
• Installation of underground pipes.
• Pipe shall be transported to the place it will be placed. Threading of the pipes will be made-up on the fabrication area.
• Make sure that the bottom of the trench is compacted.
• Prior to laying of the pipes, provide sand bag to the pipe for support and to attain the invert elevation as per approved plan.
• It shall conform to the coordinates, invert levels of the approved shop drawing.
• Provide Teflon tape for the threaded joint of pipes and fittings.
• Pipes shall be lowered by the use of A-frame with chain hoist and slings.
• If the entire pipes conform the approved coordinates and inverts levels, proceed to setting of pipes.
• Prior to hydro testing, make sure that all throughout piping system are clean.
• Plugs shall be installed in all branches. The plugs shall be installed during construction when the pipe installation is partially complete.
• Underground piping subjected to working pressure shall be partial hydrostatically tested every 100 meters. (Refer to MS for Hydro testing).
• If pipes already passed the testing requirement, proceed with the application of anti-corrosion resistant tape for underground piping. End laps between adjoining rolls of the wrap or between pipes sections shall be conform to the manufacturing standard.
• Pipes, wrapping and fittings shall be visually examined and tested using holiday testing. Any defective or damaged coating/wrapping shall be repaired or replaced.
• The minimum clearance between service water line and any other subsurface structure or utility shall be 300mm.
• For pipes under road pavements, concrete encasement shall be provided by civil works.
• Provide hazard tape directly above the concrete encasement/pipe prior to backfilling and compaction.