Pipe coupling

A pipe coupling for joining together the ends of two adjacent pipes includes 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 includes an annular chamber within the housing, an inlet for allowing fluid into the chamber, an outlet for allowing fluid out of the chamber, and an annular seal which is arranged to move within the annular chamber axially of the housing. A locking ring is provided between the annular seal and a plurality of radially movable grippers for locking the grippers to a pipe end within the housing. The locking ring includes a sloping inner surface which is engageable with a corresponding sloping outer surface on each of the grippers so that axial displacement of the locking ring under fluid pressure 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.