JOINING OF MULTILAYER THERMOPLASTIC PIPES

摘要

First and second pipes (92, 94) having at least two concentric layers of thermoplastic material are joined to form a pipe assembly. A non-planar mating surface (93, 95) is prepared on the end of each pipe. The pipes are brought into abutment at the mating surfaces (93, 95) to form a joining zone. Each of the mating surfaces (93, 95) is heated and then cooled under compression to solidify the joining zone, thereby forming a weld. Preferably separate heating processes are used to melt and join the separate layers, thereby substantially eliminating the intermingling of the layers, which may be chemically incompatible. A strong, durable joint is effected in a simple and reliable manner. Optionally, a melt flow insert is disposed between the pipes (92, 94) being joined to provide physical separation between the volumes of the different layers that are melted during the formation of the joint.