SEMI-SUBMERSIBLE STRUCTURE

摘要

A semi-submersible structure (10) including pontoons (16) and carrying at least one prime mover (22) is provided, with prime movers (22) being located in the pontoons (16). The structure (10) is a semi-submersible rig with a deck (12) supported on two pairs of columns (14, 15), each pair of columns being carried by a respective pontoon (16). Prime mover support equipment and fuel tanks (34, 36) are also located in the pontoons. Ducting for exhaust gases and air for the prime mover is provided in the columns (14, 15) and an air inlet duct (40) is over-pressured by forcing air into the duct. Extraction means is provided for urging gases through a second outlet duct (44) to prevent a build-up of back pressure. The ducts (40, 44) are provided with integrity devices to prevent ingress of potentially explosive gases and to ensure that water cannot enter the ducts.