DEVELOPMENT OF METHOD/APPARATUS FOR CLOSE-VISUAL INSPECTION OF UNDERWATER STRUCTURES (ESPECIALLY PIPELINES) IN MUDDY AND UNCLEAR WATER CONDITION

摘要

Ordinarily, the Remotely Operated Vehicles and underwater divers, even with modern illuminating lamps, would be unable to observe objects clearly in muddy or unclear underwater condition. Efforts have therefore been made to demonstrate that in such underwater condition, it is possible to perform visual inspections and observations adequately and reliably for underwater leaking structures using novel equipment. The novel equipment works by simply supplying a clear laminar flow of water which flows over the surface of the structure to be observed. A camera eye is then placed to observe through the steady flowing clear water. Different configurations of the equipment were checked and it was found that the equipment with fitted valves installed in the flooding box in-line with flowing clear water produced the best result. The volume of water required for the observations appears constant and independent of the depth of water except during the first initial stage of flooding. On the other hand, the period of time required for clear observations increases with increase in water depth. The performance of the equipment was found independent of the nature of underwater visibility. The benefits of this work ranges from leaking structures' close-visual inspection including leaking pipelines, to subsea pipeline field joint wrap damage inspection for beach pulls in cofferdams. This technique is considered cheap, robust and flexible.