Method of joining pipes by means of an electrically heatable sleeve

Claim 1

TECHNIQUE FOR JOINING PIPE, FITTINGS AND OTHER ARTICLES OF THERMOPLASTIC RESINOUS MATERIAL WHICH COMPRISES PROVIDING BETWEEN MALE AND FEMALE MEMBERS THAT ARE ADAPTED TO BE JOINED IN AN OVERLAPPING, CONTIGUOUS RELATIONSHIP AND IN A SLIP-FITTING MANNER OF COMBINING ENGAGEMENT A FORAMINOUS, GRID-LIKE, ELECTRICALLY HEATABLE SLEEVE ELEMENT THAT INTERFITS AND IS SUBSTANTIALLY COTERMINOUS WITH THE INTERFACING WALL SURFACES INTENDED TO BE OVERLAPPED AND CONTIGUOUSLY ENGAGED; POSITIONING SAID SLEEVE ELEMENT AGAINST AN INTERFACING WALL SURFACE OF ONE OF SAID MEMBERS; ELECTRICALLY ENERGIZING SAID SLEEVE ELEMENT BY MEANS OF AN ELECTRICAL CIRCUIT HAVING DIRECT CURRENT CONTINUITY WHILE IT IS SO DISPOSED TO GENERATE SUFFICIENT HEAT TO FUSE THE THERMOPLASTIC MATERIAL ADJACENT THERETO; SLIPPING THE OTHER MEMBER INTO OVERLAPPING ENGAGEMENT WITH THE FIRST MEMBER WHILE THE THERMOPLASTIC MATERIAL IS FUSED TO FORCE SAID FUSED MATERIAL TO ENVELOPE SAID SLEEVE ELEMENT AND FLOW AGAINST THE CONTIGUOUS INTERFACIAL WALL SURFACE OF SAID MEMBER BEING SLIPPED INTO ENGAGEMENT; AND WELDING SAID MEMBERS INTO PERMANENT SEALED ENGAGEMENT BY COOLING THE FUSED INTERFACIAL PORTION OF THE THERMOPLASTIC RESINOUS MATERIAL IN SAID ADJOINED MEMBERS.