This International Standard specifies methods of test for joints with a locked socket and spigot, including double-socket joints, and with elastomeric seals, for buried and non-buried glass-reinforced thermosetting plastics (GRP) piping systems. This standard is applicable only to the joint, and specifies methods of test to prove its design. It assumes that the joint will be exposed to the effects of hydrostatic end thrust. The tests are applicable to locked socket-and-spigot joints intended to be used in buried or non-buried applications. With the exception of the bending test, these tests are applicable to joints with pipes and fittings of all nominal sizes. The bending test is applicable to joints with pipes and fittings up to and including DN 600. The tests are suitable for evaluating joints intended for applications in which liquids are conveyed at particular temperatures.