Abstract: An adjustable length piping union having telescoping tubes. An inner tube has outer ring grooves whose bottom walls slope, and whose axial width is greater than the width of an O-ring contained in them. This enables an easier reduction in length than increase in length. A ledge permits passage of the rings for assembly, but frustrates the separation of the tubes.

Abstract: A pipe coupling particularly adapted for use with plastic pipe carrying fluid at high pressure has a body section from which there extend in the axial direction, two concentric sleeve sections with a concentric annular space between them. The end of a pipe to be coupled is fitted over the internal sleeve and an annular wedge is placed in the annular space between the pipe and the external section. A nut having an annular sleeve is threaded to the external section so that the annular nut sleeve enters the annular space and engages the wedge. Torquing of the nut urges the wedge along a camming surface into tight engagement with the pipe, thus deforming it to prevent its withdrawal from the coupling. The tightness of the coupling is enhanced by variation of the diameter of the internal sleeve in the vicinity of the wedge and by ridges on the internal sleeve into which material of the pipe is forced by the wedge to flow.

Abstract: A unitary fitting for fluid piping systems. A body has a socket member, and a hub member fits in the socket member. The members define the bottom and sides of a ring groove, and a resilient sealing ring fits in the groove. Each of the members has a wall which is adapted to be brought into abutment with the other, and a structural joinder joins the walls. A preferred means to form the structural joinder is to rotate the hub member in the socket member while the walls are in abutment, whereby the frictional forces will generate sufficient heat to cause the walls to fuse together, especially when they are formed of a thermoplastic plastic material, such as polyvinyl chloride.