High density polyethylene (HDPE ) is made in accordance with the requirements of CP 312 Part 1 and 3 and BS EN 123244-1 , 2, 5:2002 . When pipes for the use of rehabilitation, the pipes must be of short sections that correspond to the requirements of the chosen method and the available workspace in looks or trees.
Longer lengths may be used for the new setup where the open trench methods conventional building are used . The base polymer is polyethylene with a density higher than 930 kg/m3 derivatives being determined according to BS 3412 Method requires . The base polymer is blended with additives which are necessary for the manufacture , storage and use of HDPE pipes for sewer pipes , including antioxidants , carbon black and UV stabilizers . The tube -shaped material must have a thermal stability of at least 15 minutes when tested according to the method of the isotherm for the differential thermal analysis . The tube ends should be cut , clean and straight . The connection of pipes and fittings, polyethylene system must be in accordance with the recommendations of the pipe manufacturer subject to the approval of the Engineer . HDPE pipes are used for non-pressure sewage gravity that are larger than the inner diameter of 250 mm . PVC pipes used for gravity discharge of a diameter of 250 mm or less.
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