Abstract: This invention relates to joining a ring to a tube passing through the ring, for example, or for joining two pipes end to end by means of a ring. In one form of the invention the ring is radially compressed during relative rotation of the parts to be joined by a pressure substantially uniformly distributed around the ring to develop frictional heat and to cause penetration of the ring into the tube or aligned pipes. The relative rotation is then stopped and a friction weld is formed.Many variations are possible: for example a rotating internal ring may be expanded by radial pressure and thereby friction welded to a tube or across the junction of two pipes.