Specifications Part 1 - Water Supply, Sewerage and Tube Well Works

8.10.6 Pipes shall be stored such that they are not in contact with direct sunlight,lubricating or hydraulic oils, petrol, solvents and other aggressive materials.8.10.7 Scores or scratches to a depth of greater than 10 % or more of wall thicknessare not permissible; any pipes having such defects should be strictly rejected.8.10.8 PE pipes should not be subjected to rough handling during loading andunloading operations. Rollers shall be used to move, drag the pipes across anysurface.8.10.9 Only polyester webbing slings should be used to lift heavy PE (>315mm) pipesby crane. Under no circumstances, chains, wire ropes and hooks be used onPE surface.8.10.10 Pipes shall not be dropped to avoid impact or bump. If any time duringhandling or during installation, any damage, such as gouge, crack or fractureoccurs, the pipe shall be repaired if so permitted by the competent authoritybefore installation.8.11 Lowering, Laying of pipes8.11.1 IS: 7634 shall be applicable. Before using the pipe following precautions/checkshall be taken.8.11.2 Each pipe shall be thoroughly checked for any damages before laying and onlythe pipes which are approved by the Engineer shall be laid.8.11.3 While installing the pipes in trenches, the bed of the trench should be level andfree from sharp edged stones. In most cases, the bedding is not required, aslong as the sharp and protruding stones are removed, by sieving the dug earth,before using the same as a backfill material. While laying in rocky areassuitable bed of sand or gravel should be provided. The fill to about 10 to 15 cmabove the pipe should be fine sand or screened excavated material. Wherehard rock is met with, bed concrete 15 cm thick of grade M-15 or 20 cm thicksand bed as approved by the engineer may be provided.8.11.4 As PE pipes are flexible, long lengths of fusion-jointed pipes having joints madeabove ground can be rolled or snaked into narrow trenches. Such trenches canbe excavated by narrow buckets.8.11.5 During the pipe laying of continuous fusion jointed systems, due care andallowance should be made for the movements likely to occur due to the thermalexpansion/contraction of the material. This effect is most pronounced at endconnections to fixed positions (such as valves etc.) and the branchconnections. Care should be taken in fixing by finishing the connections at atime the length of the pipe is minimal (lower temperature times of the day).8.11.6 For summer time installations with two fixed connection points, a slightly longerlength of PE pipe may be required to compensate for contraction of the pipe inthe cooler trench bottom.8.11.7 The final tie-in connections should be deferred until the thermal stability of thepipeline is achieved.8.11.8 The flexibility of polyethylene pipes allows the pipe to be cold bend. The fusionjointed PE pipe is also flexible as the plain pipe. Thus the total system enablesUrban Administration & Development Department Page 93