WELDABLE PIPE FITTINGS

摘要

A method of forming weldable pipe fitting including a thermoplastic sleeve comprising the steps of incising around the internal wall of the sleeve a helical cut inclined to the surface of the wall along the line of the cut, the cutting tool and its angular relationship to the bore of the sleeve being chosen such that during incision an internally extending flap of thermoplastic material produced by the incision is caused to open out and deform transverse to the direction of incision whereby a helical cavity is formed within the sleeve wall; feeding into said cavity an electrically conducting wire; anchoring the ends of the electrical wire; and treating the internal surface of the sleeve so as to hold the wire within said cavity.