PIPE COUPLING

A pipe coupling ( 10 ) for joining together the ends of two adjacent pipes includes a housing ( 12 ) which defines a generally central bore ( 13 ) along a central axis of the housing for receiving the ends of the two adjacent pipes, and a locking arrangement ( 14 ) at each end of the housing ( 12 ) for locking the pipes to the coupling. Each locking arrangement ( 14 ) includes an annular chamber ( 23 ) within the housing, an inlet for allowing fluid into the chamber, an outlet for allowing fluid out of the chamber, and an annular seal ( 24 ) which is arranged to move within the annular chamber axially of the housing. A locking ring ( 26 ) is provided between the annular seal ( 24 ) and a plurality of radially movable grippers ( 30 ) for locking the grippers to a pipe end within the housing. The locking ring ( 26 ) includes a sloping inner surface ( 28 ) which is engageable with a corresponding sloping outer surface ( 32 ) on each of the grippers ( 30 ) so that axial displacement of the locking ring under fluid pressure within the annular chamber ( 23 ) causes radial displacement of the grippers ( 30 ) towards the central axis of the housing ( 12 ) for clamping the pipe end within the housing.