UNDERWATER WELLHEAD APPARATUS

1,215,830. Mills &c. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 27 Nov., 1968 [29 Nov., 1967], No. 56310/68. Heading E1F. [Also in Division B3] A manipulator for carrying out operations at an underwater wellhead and controlled from a base positioned above the water's surface has an arm provided with a gripper carrying a wrench socket. The arm is mounted normal to the vertical axis of the manipulator to be moved along and rotates about the axis. The mamipulator runs on a track in a wellhead assembly as described in Specification 982070. The gripper comprises movable and fixed jaws 54, 56 mounted on a tube 53 rotated within the arm body 28 by a motor 40 having a spline coupling 42 with a spindle 30 suppartimg the tube, and the socket 77 is formed in the fixed jaw 56. The spindle has a piston 34 permitting the gripper to be extended from the arm body by fluid pressure. The jaw 54 is connected to a piston 65, the arrangement being that the jaw 54 is closed by fluid pressure and opened by a spring 68. In a modification the movable jaw is the lower one and is opened by a spring mounted in the fixed jaw.