Abstract: An electro-fusion pipe coupler includes an outer shell and an electric resistance heating coil secured therein by an intervening layer of injection moulded thermoplastic material. The coupler is made by winding the wire onto a core which consists of two separable parts inserting the core into the tubular shell, attaching contacts to the wire ends and inserting them into holes provided in the shell, and injecting molten material into the space defined between the core and the shell to form the layer. For injecting the material the core parts define therebetween radial runners connected to a central sprue inlet and opening at respective outlets spaced around the core.

Abstract: An electro-fusion fitting for coupling thermoplastic pipes incorporates a heating coil (2) and has a resistor (6) with a value chosen in accordance with the power to be supplied to the coil connected between a main terminal (4) and an auxiliary terminal (5). Control apparatus is adapted to sense the resistance value and supply electric current to the coil for a predetermined time set automatically according to the resistance value.