A METHOD FOR MANUFACTURING A HOTWATER PROOF PLASTIC PIPE

摘要

The method of manufacturing a composite pipe includes extruding an inner pipe from a polyethylene or polyethylene copolymer mix having a cross-linking agent such as peroxide homogeneously dispersed therein. The extrusion takes place below the decomposition temperature of the agent to prevent cross-linking. Thereafter, an outer jacket is positioned over the inner pipe and the composite pipe is heat treated, usually in coil form, at a temperature to cause cross-linking of the inner pipe. A positive gas pressure is maintained in the pipe during heat treating at least until the cross-linking has progressed sufficiently to prevent the pipe from collapsing. The outer jacket acts as the reinforcement and maintains the shape and inside diameter of the inner pipe during processing under pressure.