| 摘要 |
PROBLEM TO BE SOLVED: To certainly bond a pipe body made of a thermoplastic resin to be connected and an electric fusion joint having a heating element built therein even if there is a slight gap between the outer diameter of the former and the inner diameter of thre latter. SOLUTION: Heating strands 4a, 4b are coated with a coating material composed of a thermoplastic resin containing a foaming agent decomposed and foamed only at a predetermined temp. and wound in a coil from to obtain heating elements 3a, 3b which are, in turn, integrally provided to the inner peripheral surface of a sleeve main body 2 by insert molding to form an electric fusion joint 1. Pipes 8a, 8b made of a thermoplastic resin are inserted into this electric fusion joint 1 to supply a current to the heating elements 3a, 3b to heat the heating elements to predetermined temp. and the foaming agent in the coating material is decomposed and foamed to integrally fuse and bond the sleeve main body 2 and the pipes 8a, 8b. |
