GB1475982A - Pipe and method of forming same - Google Patents

Abstract

1475982 Moulding spigots and sockets UNITED STATES PIPE & FOUNDRY CO 9 Jan 1976 [3 Feb 1975] 888/76 Heading B5A [Also in Division F2] Pipes having spigot and bell ends for interfitting one with the other (see Division F2) comprise, for each pipe a hollow metal cylinder 18 on the exterior surface of which is moulded an annular plastics member 26, Fig. 4, at the spigot end and on the interior surface of which is -moulded an annular plastics member 44, Fig. 5, at the bell end of the pipe. In Fig. 4 the cylinder 18 extends vertically and is located within a spigot mould 56 by hinged members 62, blocks 66 of the same material as the spigot end member 26 preventing the cylinder from contacting the mould. The plastics material, e.g. a urethane elastomer is then cast in the mould a preformed ring 64 preventing its loss inside the cylinder. A tensioned rod 34 may be wound round the end of the cylinder 18 for reinforcement. A groove 36 for an 0-ring is also formed during the moulding. The annular member 44 at the bell end of the pipe is moulded in a similar fashion (Fig. 5) hinged locating members 70 contacting the outer surface of the cylinder 18. The annular members 26, 44 are formed with radially projecting flanges 28, 40, 50, 52 and after the moulding processes above inner and outer concrete layers (not shown) are provided on the cylinder 18 between the flanges at the pipe ends. In an alternative moulding process, Fig. 9, the cylinder 18 is held horizontally and moulds 88, 90 are positioned around the ends of the cylinder, the moulds incorporating inflatable seals 108, 110, 112, 114. The plastics material is injected at the lowest point of the mould cavities and vents 122 allow escape of displaced air. Inner and outer concrete layers are then provided on the cylinder 18 between the flanges on the annular plastics end members as before.