GB1475305A - Pipes of synthetic plastics material - Google Patents

Abstract

1475305 Encasing end of pipe REDLAND PIPES Ltd 9 July 1974 [10 July 1973] 32771/73 Heading B5A [Also in Division F2] The end of a synthetic resin pipe 2 is surrounded by a mould 3 which is filled with synthetic resin that hardens to form a shaped spigot having an external annular groove at 9 for a sealing ring. As described, an extruded plastics, or a glass fibre reinforced plastics pipe 1 is roughened at its end, and a two-part metal or plastics mould 3 is coated with release agent and erected around the pipe end. The mould is clamped on flanges 4, and seals against the pipe by strips 8 of self-adhesive foamed plastics stuck on to the pipe. The mould and pipe end are heated to 110‹ C., and a polyester or urethane resin (from a mixture of one or more polyols with diphenyl methane) is injected into the mould through lower semicircular holes 11. The resin feed is stopped when air escaping from upper semicircular holes 11a is replaced by resin which is fed by tubes into, and partly fills, a small reservoir. Curing occurs at at least 110‹ C., with the reservoir resin preventing air being sucked back into the mould on shrinkage of the resin. The mould 3 is removed with, the sealing strips 8, or the latter are left in position, and a rubber sealing ring is inserted in the groove at 9. The mould 3 can also define a screw-thread on the spigot (see Fig. 5, not reproduced). The extruded pipe 2 has a socket adhered to its end opposite the spigot, while the glass fibre reinforced pipe has an integrally moulded socket. Alternatively, the mould 3 can be used to produce oppositely handed threads at each end of the pipe 2, to allow connections of two similar pipes by an internally screwthreaded coupling.