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2 .2 . 8 . Polyethylene (PE) Pressure Pipe Installation (Cont' d) the trench to prevent damage or twisting of the Care shall be exercised when lowering pipe into p g 8 pipe. Drawmi s Pipe shall be laid to fines and grade shown on the g with bedding and backfill as shown on the Drawings . When laying is not in progress, including lunchtime, the open ends of the pipe shall be closed by fabricated plugs, or by other approved means . Pipe shall be stored on clean level ground to prevent undue scratching or gouging. The handling of the pipe shall be in such a manner that the pipe is not damaged by dragging it over sharp and cutting objects. The maximum allowable depth of cuts, scratches or gouges on the exterior of the pipe is 10 percent of wall thickness. The interior pipe surface shall be free of cuts, gouges or scratches. Sections of pipe with cuts, scratches or gouges exceeding five percent of the pipe wall thickness shall be removed completely and the ends of the pipeline rejoined. The pipe shall be joined by the method of thermal butt fusion, as outlined in ASTM D2657 . All joints shall be made in strict compliance with the manufacturer' s recommendations . Mechanical connections of the polyethylene pipe to auxiliary equipment such as valves, pumps and tanks shall be through flanged connections which shall consists of the following : 1 . A polyethylene flange shall be thermally butt-fused to the stub end of the pipe . A carbon steel back-upring shall be used on both sides of the connection prior to thermally butt-fusing the polyethylene flange. 2 . A 316 stainless steel back up ring shall mate with a 316 stainless steel flange. 3 . Ductile iron back up rings shall mate with cast iron flanges Flange connections shall be provided with a full face neoprene gasket. All PE pipe must be at the temperature of the surrounding soil at the time of backfilling and compaction. No single piece of pipe shall be laid unless it is straight. The centerline of the pipe shall not deviate from a straight line drawn between the centers of the openings at the ends of the pipe by more than 1 / 16 in per foot of length. If a piece of pipe fails to meet this requirement check for straightness, it shall be rejected and removed from the site. Laying instructions of the manufacturer shall be explicitly followed. 26