Conception and development of method / apparatus for close-visual inspection of subsea structures in underwater poor visibility condition

Attempt has been made to demonstrate that in unclear water to zero underwater visibility conditions, where ordinarily, underwater divers would be unable to observe objects, it is easily possible to perform inspections and observations adequately and reliably for underwater structures, especially leaking subsea pipelines by simply supplying clean streamlined steady (laminar) flow of water which displaces the unclear water and flows over the surface of the structure to be observed. A camera eye is then placed to observe through the steady flowing clean water and transmit details to the topside engineers via personal computers. Different configuration of the equipment was checked and it was found that the equipment with fitted check valves and on/off valve installed in the flooding box in-line with the flowing clean water produced the best result. Also, where ‘over-pressure’ is defined as the difference between the supply clean water pressure from topside and the sea water column pressure (head), best results were found at over-pressure less than 1-psig. The volume of water required for the observations appears constantly independent of depth of water except during the first initial stage of flooding. On the other hand, period of time required for clear observations increases with increase in water depth. The performance of the equipment was found independent of nature and degree of underwater visibility. The benefits of this work has been discussed, ranging from leaking structures’ close-visual inspection including pipelines, to subsea pipeline field joint wrap damage inspection for beach pulls. It has also been pointed out that this technique is cheap, robust and flexible. However, further work is still required to adequately establish the theory and extend the Attempt has been made to demonstrate that in unclear water to zero underwater visibility conditions, where ordinarily, underwater divers would be unable to observe objects, it is easily possible to perform inspections and observations adequately and reliably for underwater structures, especially leaking subsea pipelines by simply supplying clean streamlined steady (laminar) flow of water which displaces the unclear water and flows over the surface of the structure to be observed. A camera eye is then placed to observe through the steady flowing clean water and transmit details to the topside engineers via personal computers. Different configuration of the equipment was checked and it was found that the equipment with fitted check valves and on/off valve installed in the flooding box in-line with the flowing clean water produced the best result. Also, where ‘over-pressure’ is defined as the difference between the supply clean water pressure from topside and the sea water column pressure (head), best results were found at over-pressure less than 1-psig. The volume of water required for the observations appears constantly independent of depth of water except during the first initial stage of flooding. On the other hand, period of time required for clear observations increases with increase in water depth. The performance of the equipment was found independent of nature and degree of underwater visibility. The benefits of this work has been discussed, ranging from leaking structures’ close-visual inspection including pipelines, to subsea pipeline field joint wrap damage inspection for beach pulls. It has also been pointed out that this technique is cheap, robust and flexible. However, further work is still required to adequately establish the theory and extend the design of the equipment to operate remotely and diverless