The tubular, thermoplastic plastics support (26) fits into a tubular holder of a thermoplastic plastics pipe, and is clamped to the connecting part (18). The closure part (16) has a flanged flank (22) forming an annular protruding groove (24) into which the end of the tubular support is clamped. The tubular support is positioned in a cavity (20) in the connecting part and, on its end, rests against a thrust surface (21) facing the groove. The connection is made of brass, steel or refined steel. The guide surface (16a) of the closure part has profiled grooves engaging with protuberances on the tubular support.