Abstract: An electrofusion joint includes an electrical heating wire embedded in its inner peripheral region. The electrofusion joint can be fitted to an end of a plastic pipe. By supplying electrical current to the electrical resistance heating wire the interface between the joint and the pipe are fusion bonded. In order to allow easy determination of the completion of fusion bonding, the electrofusion joint is provided with an annular groove in the outer peripheral surface extending to a region of the joint near the electrical resistance heating wire. A pin or bar-like core member is located at and extends upwardly from the center of the groove.

Abstract: This invention relates to an electrofusion joint, in which the electric power is supplied to a heating wire, which is buried in a resin, to melt the resin and thereby connect pipes together, and more particularly to an electrofusion joint, in which a member to be connected to a sensor-carrying connector is molded unitarily with the joint with a code member, which is to be detected by the sensor, molded unitarily with the member to be connected. A code displayed on the code member is read by the sensor and judged by a control unit as the quantity of power supplied to the heating wire through the connector and the member to be connected, or as the time during which the electric current is thus supplied to the heating wire, whereby an electric power of a predetermined magnitude is supplied thereto.

Abstract: A process for injection compression molding ultra high molecular weight polyethylene having an intrinsic viscosity of 3 dl/g or higher measured at 135.degree. C. in decalin and a melt index of 0.01 g/10 min or less comprises,(a) heating the ultra high molecular weight polyethylene to 170.degree.-240.degree. C.,(b) adjusting the volume of the mold cavity V.sub.1 equal to the volume of the molded article V.sub.0,(c) injecting ultra high molecular weight polyethylene having a volume V.sub.0 into the mold cavity through a runner portion at a shear rate of at least 20,000 sec.sup.-1,(d) instantaneously expanding the mold cavity to adjust its volume V.sub.1 to satisfy the relation:1.2 V.sub.0 .ltoreq.V.sub.1at a time from T.sub.1 (immediately before completion of injection) and a time T.sub.