Abstract: A section of metal pipe has one end connected to a main line pipe. A hollow cylindrical plastic piston having a plurality of O-rings thereabout is slidingly and sealingly received within the open end of the metal section. A plastic carrier pipe is fixedly received within the outwardly facing end of the piston for suitable interconnection to other equipment. First and second limits are spaced along the pipe section to locate the piston within the pipe section. These limits may be flanges machined into the pipe section, or the pipe section may be rolled so as to include an inwardly directed, circumferentially extending ridge. In a further version, the transition joint is incorporated into a riser arrangement in which the plastic carrier is located within an outer tubing or pipe and held spaced from the tubing walls throughout the entire length of the tubing. Also, replacement of a service line is accomplished by threading plastic pipe through original line and terminating via transition joints at each end.