Pipe coupling

A pipe coupling for joining together the ends of two adjacent pipes, the coupling including a housing formed by a body portion and a pair of end caps threaded onto respective open axial ends of the body portion, the body portion defining 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, wherein each pipe is to be inserted into a respective open end of the bore in an axial inward direction and removed from that open end of the bore in an axial outward direction, each locking arrangement including:

• an annular chamber within the housing and formed between portions of the body portion and the respective end cap;
• an inlet for allowing fluid into the chamber;
• an annular seal which is arranged to move within the annular chamber axially of the coupling;
• a plurality of grippers disposed adjacent respective open ends of the bore and each having an axially outer end engaged by a respective end cap and being radially moveable towards the central axis of the housing from an inoperative condition to an operative condition, each gripper further including:
• a gripping formation arranged, in the operative condition of the gripper, for operatively gripping a pipe inserted into the bore of the body portion, and for releasing the pipe in the inoperative condition of the gripper, and
• a locking formation including a radially inwardly open recessed area in the gripper into which a radially outwardly projecting portion of the body portion extends, the recessed area including an axially outwardly facing surface facing toward the respective open end of the bore and arranged to move generally radially toward the central axis into axially facing locking relationship with an axially inwardly facing surface of the projecting portion of the body portion wherein the body portion opposes forces tending to pull the gripper from the respective open end of the bore, in the operative condition of the gripper, to axially lock the gripper to the housing, and to move generally radially away from the central axis out of said axially facing locking relationship in the inoperative condition of the gripper;
• and
• at least one locking element between the annular seal and the grippers for locking the grippers to the body portion and to a pipe end within the body portion, the or each 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 fluid pressure within the annular chamber causes radial displacement of the grippers into the operative condition, axially locking the grippers to the body portion and clamping the pipe end within the body portion.