Abstract: A plug-in coupling for a pipe, especially for water conduits, includes a coupling sleeve receiving the pipe end, includes a sealing ring which is inserted into the coupling sleeve, and includes a locking ring which is mounted upstream of the sealing ring in the plug-in direction of the pipe end and forms retaining claws which protrude with respect to the pipe end and are inclined in the plug-in direction. The plug-in coupling also includes an annular body which is similarly mounted upstream of the sealing ring and is supported axially in the plug-in direction in relation to the coupling sleeve. The annular body includes a protective ring for surrounding the face end of the pipe end from the outside, which protective ring is connected via a predetermined breaking connection.

Abstract: A device includes a connection nipple for connecting to a plastic tube. The connection end of the plastic tube, which is provided with a frontal chamfer at least in the area of the internal diameter, is axially fixed between the connection nipple and a clamping sleeve with at least one sealing ring held interposed in the profiled connection nipple. The connection nipple has at least one radially outwardly protruding stop , which is displaceable radially inward via the frontal chamfer in the area of the internal diameter of the connection end, the stop being situated in front of the sealing ring viewed in the insertion direction.

Abstract: The invention relates to a plug-in coupling for a pipe (3), especially for water conduits, comprising a coupling sleeve (1) receiving the pipe end (2), a sealing ring (4) which is inserted into the coupling sleeve (1), a locking ring (6) which is mounted upstream of the sealing ring (4) in the plug-in direction of the pipe end (2) and forms retaining claws (7) which protrude with respect to the pipe end (2) and are inclined in the plug-in direction, and an annular body which is similarly mounted upstream of the sealing ring (4) and is supported axially in the plug-in direction in relation to the coupling sleeve (1). In order to provide advantageous constructional conditions it is proposed that the annular body comprises a protective ring (12) for surrounding the face end of the pipe end (2) from the outside, which protective ring is connected via a predetermined breaking connection (13).

Abstract: A device for connecting a plastic tube (1) to a connection nipple (2) is described, the connection end (4) of the plastic tube (1), which is provided with a frontal chamfer (8) at least in the area of the internal diameter, being axially fixed between the connection nipple (2) and a clamping sleeve (3) with at least one sealing ring (5) held interposed in the profiled connection nipple (2). In order to provide advantageous connection conditions, it is proposed that connection nipple (2) have at least one radially outwardly protruding stop (14), which is displaceable radially inward by means of the frontal chamfer (8) in the area of the internal diameter of the connection end (4), the stop (14) being situated in front of the sealing ring (5) viewed in the insertion direction.