Pyrotechnic collars for fusion welded thermoplastic pipe joints - for facilitating prodn. of joints in situ

摘要

A heated insert for melting the interfacial surfaces of a thermoplastic pipe coupling comprises an annular array of flat prongs which receive heat conducted from combustion of a pyrotechnic material in an external metal collar. Method is suitable for welding socket/spigot or pipe/sleeve joints in pipes or pipe fittings of 30 mm.-3 m. bore of materials with m. pt. up to 400 degrees C; esp. for making joints in situ in remote places, because the collars and their charges are more readily carried out and maintained than alternative equipment for heating inserts by electrical resistance or induction heating or for assembling force fit joints.