The Durability of a Low-pressure Gas Distribution System of Ductile PVC

One of the options for a low-pressure gas distribution system is the use of ductile PVC pipes and joints. The long-term performance of ductile PVC pipes has been reported in a number of previous studies. In this paper the long-term performance of the socket joints, in which elastomeric (NBR) sealing rings are used, is evaluated. The long-term quality of socket joints in ductile PVC pipeline systems has been determined by various tests on a number of excavated joints, which have been in operation for more than 20 years. Leak tightness determined according to the present specifications did fulfil all requirements. The quality of the rubberrings , established by e.g. tensile testing and hardness tests, was also still at the level of new rubberrings. The socket joints started only to leak at deflections of the pipes far exceeding the deflection levels met in field practice. The compression set of the excavated samples was also rather low and extrapolated to long times will not exceed a maximum required value of 70 % before 50 years. These results once again show that ductile PVC pipe systems for low-pressure gas distribution exhibit an excellent (long-term) performance.