Pipe coupling

A pipe coupling for joining together the ends of two adjacent pipes, the coupling including a housing which defines a generally central bore along a central axis of the housing for receiving the ends of the two adjacent pipes, and a locking arrangement at each end of the housing for locking the pipes to the coupling, each locking arrangement including:

• an annular chamber within the housing;
• an annular, dynamic seal which is movable within the annular chamber, axially of the housing;
• an inlet for allowing fluid into the annular chamber;
• an outlet for allowing fluid out of the annular chamber and out of the housing;
• a plurality of radially movable grippers;
• at least one locking element between the dynamic seal and the grippers for locking the grippers to a pipe end within the housing, the at least one locking element including a sloping inner surface which is engageable with a corresponding sloping outer surface on at least one of the grippers so that axial displacement of the at least one locking element under the force of a pressurized actuation medium within the annular chamber causes radial displacement of the grippers towards the central axis of the housing for clamping the pipe end within the housing;
• and
• a pressure release mechanism arranged to release actuation medium from the annular chamber and from the housing through the outlet when the pressure thereof within the annular chamber reaches a predetermined magnitude at which the grippers are firmly clamped to the pipe and are locked in position by the at least one locking element, for providing an indication that the pipe is locked within the pipe coupling.