JPS57195591A - Production of clad pipe - Google Patents

Abstract

PURPOSE:To facilitate production of superposed double pipes by inserting pipe expanding materials of a coefft. of thermal expansion larger than that of the superposed double pipes into an inside pipe, and tightening the pipe expanding material with tightening jigs of a coefft. of thermal expansion likewise larger than that of said pipes, then heating the pipes to a temp. higher than the diffusion temp. and cladding the pipe. CONSTITUTION:Pipe expanding materials 5 of a coefft. of linear expansion larger than that of an outside pipe 1 and an inside pipe 2' superposed therein are divided to a plurality in the circumferential direction and are inserted into the pipe 2'. Further, the materials 5 are tightened by tightening jigs 7, 7-9 of a coefft. of linear expansion larger than that of the pipes 1, 2' to intensify the joining and tightening of the pipe 2' and the pipe 1. These pipes are contained in a furnace, whereby they are heated to a temp. higher than the diffusion temp. The jigs 7, 7-9 and the materials 5 receive restraints in the axial direction and expand in the diametral direction upon elevation of temp., whereby the pipes are expanded and the joining parts are tightened more strongly and well diffused.