Importance

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Abstract

The invention provides a system and method for joining plastic members including induction heaters fabricated from a conductive wire coated with a ferromagnetic material and providing ratios of at least 4 to 1 between the areas over the spaces between wires and the area of the wires surrounding the open spaces; the heaters being located preferably between plastic members to be joined. The heaters may be located adjacent the two ends of a plastic connector adapted to receive a pipe in at least one and probably two ends with the heaters being activated preferably by induction heating to produce welding of the plastics to one another. One form of heater is fabricated on a hollow cylindrical mandrel having helical grooves in which the wire is wound and having radial holes arranged in axially extending rows spaced circumferentially about the mandrel so the axially extending wires may be spot welded to the wires in the helical grooves at each hole. Rings of wire may also be held together by axially extending grooves. Saddle fittings and patches may also be applied to pipes or other plastic members employing such heaters. Induction coils in the form of clamshell and jaw-like structures may be employed as appropriate to energize such heaters and flexible coil structures may also be employed.

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First Claim