Patent ID: 7134204

Claim:
A method of installing a restraint system in a belled end of a plastic pipe which is used to form a pipe coupling, the method comprising the steps of: providing a mandrel with an inner end and an outer end and having an outer working surface; installing a first component of a restraining/sealing mechanism at a first circumferential position on the outer working surface; installing at least a second component of the restraining/sealing mechanism at an additional circumferential position on the outer working surface; heating a female end of the plastic pipe; forcing the heated female end of the plastic pipe over the working surface of the mandrel and over both the first and the second components of the restraining/sealing mechanism, whereby the heated female pipe end of the plastic pipe flows over both components of the restraining/sealing mechanism to form a spaced pair of retention grooves and then again contacts the working surface of the mandrel; cooling the heated female end of the plastic pipe; retracting the cooled female end of the plastic pipe and the retained components of the restraining/sealing mechanism from the working surface of the mandrel; and wherein the second component of the restraining/sealing mechanism is a relatively rigid gripper ring.