GB1367837A - Apparatus for underwater operations - Google Patents

Abstract

1367837 Diving chambers, subaqueous struc- SUBSEA EQUIPMENT ASSOCIATES Ltd 1 May 1972 [28 June 1971] 20208/72 Heading E1H An installation for underwater servicing of, e.g. a well head 81 comprises a base member 2 secured to and surrounding the well head and provided with a flat surface to receive a work bell 5 lowerable from, e.g. a ship by a pipe (6) Fig. 1 (not shown), the bell 5 having an external control chamber 13 separated from the bell by a watertight door and equipped with an external watertight door 16, and a transfer chamber 10 having a ballast tank 63, propulsion means 14 and a watertight door 61, 62 leading to a trunk 15 cooperable with the surface of the control chamber 13 around the door 16. In operation, the transfer chamber 10 descends to inspect the well head 81 and base member 2 and returns to the surface before the workbell 5 is lowered, the bell being filled with air via pipe (6) and valves 31, 79. When the bell 5 is guided into position on base member 2 the upper end of pipe 6 is opened to atmosphere before the pipe is withdrawn, automatically closing valve 31. The transfer chamber 10 is now lowered into position over door 16 and a pump 64 evacuates the water from trunk 15 via pipe 68. The workcrew descend into trunk 15 and connect up electrical and gas supply connectors 54, 56 before entering chamber 13. Here they check the atmosphere in bell 5 by means of telemeter SO, before entering the bell, one operator remaining in the chamber 13. If the atmosphere in bell 5 is, or becomes, unsatisfactory, the crew remain in chamber 13, door 17 is closed and the bell filled with water via pipe 38 and valves 74, 75, the gas being exhausted via pipe 76 and valve 77. The water is then pumped out via pipe 38 valves 74, 73 and pump 37, and the bell filled with nitrogen at atmospheric pressure from cylinders 43 via pipe 44 and valve 78. The workcrew can now re-enter bell 5 equipped with self-contained breathing apparatus. On completion of their work the crew return to the chamber 13 and fill the bell with water. The atmosphere in chamber 13 is rendered breathable by absorption of impurities and addition of oxygen. The crew then re-enter transfer chamber 10, and open valve 72 to flood the trunk 15 whereupon the chamber 10 may return to the ship. (For Figures see next page)