Abstract: The open end inner periphery of a socket is provided with an annular groove, and at a suitable sufficient distance from the annular groove axially toward the innermost side of the socket a seal member stopping projection extends from the inner surface of the socket toward the outer peripheral surface of a spigot. A split lock ring is fitted in the annular groove. The outer peripheral surface of the spigot is provided with a projection which is disposed between the split lock ring and the stop projection and which is axially movable therebetween along with the spigot and adapted to engage with them at the ends of its travel. A seal member is disposed between a seal member supporting surface disposed inwardly of the stop projection and the outer peripheral surface of the spigot. This seal member is urged toward the stop projection by an urging device.

Abstract: A spigot is inserted into a socket, with a seal packing pressed from the opening side of the socket into an annular space defined between the socket and the spigot, a lock ring fitted in an annular groove formed in the inner peripheral surface of the pocket inwardly of the seal packing, and an engaging projection provided on the outer periphery of the front end of the spigot for axial engagement with the lock ring. The lock ring is a split lock ring which can be inserted from the annular space between the socket and the spigot toward the innermost part of the socket and has a diametrically expanding force. The depth of the annular groove is controlled so as to allow the radially inner region of the lock ring fitted in the groove to engage the engaging projection. A back-up ring is disposed between the seal packing and the split lock ring and the mutual abutting surfaces of the split lock ring and back-up ring are conical surfaces tapering toward the front end of the spigot.

Abstract: A joint connecting the plug of one pipe to the socket of another pipe and permitting relative axial movement between the pipes includes a step surface formed on the end of the plug and engageable by a split lock ring fitted into an annular groove formed in the inner surface of the socket. The lock ring is contractable into fitted relation with the plug and is provided at its ends with overlapping portions engageable by a retaining member insertable through the clearance between the socket and plug to maintain the lock ring in contracted position. The overlapping portions are preferably provided on separate pieces adjustably mounted on the ends of the split lock ring. A jig, insertable through the clearance between the plug and the socket into engagement with the ends of the lock ring, is provided for contracting the lock ring prior to the insertion of the retaining member.