PURPOSE: To provide a method capable of conducting flange connection of composite pipes each formed by providing a thermoplastic resin layer on the inner surface of a metal pipe, especially, a metal pipe having a welded seam in the longitudinal direction thereof with excellent inner pressure-resistant strength without using a packing.
CONSTITUTION: The pipe end parts of composite pipes each of which is formed by applying a thermoplastic resin layer to the inner surface of a metal pipe are turned outwardly to be formed into flange parts 10 and annular protruding parts 121 are formed to the surfaces of the inside thermoplastic resin layers 120 continued to the inner surfaces of the pipes of the flange parts 10 under heating by a mold and the flange parts 10 of both pipe ends are held by holding members 2 to mutually bring the annular protruding parts 121 of the thermoplastic resin layers 120 of the flange parts to a pressure contact state. The flange parts can be formed by partially turning over the pipe end parts outwardly and subsequently forming the semi-processed end parts into a flange shape under heating by a mold and the thermoplastic resin layers having the annular protruding parts 121 can be also formed by injection molding.
ENOMOTO SEIICHI
MATSUMOTO KOJI
