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7872 |
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Wednesday, September 13, 2023, Brüssel 2:00 PM Offshore applications |
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Underwater Weld Defect Excavations on Subsea Structures Using Hydro-Carbon Arc Gouging |
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Earl Toups* / DCN, United Kingdom Christian Rowolt / DCN, United Kingdom |
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This case study explains the adaptation of Air Carbon Arc Gouging, commonly used for excavating weld defects on the surface, for underwater use. A waterproof carbon electrode and the use of water in place of air are the key differences. The offshore jacket repair campaign involved the excavation of four each weld defects to perform hyperbaric weld repairs. While completely removing the defect, the excavation must produce a suitable grove profile for welding. Hydro-Carbon Arc Gouging is not commonly used in the offshore industry; however, the benefits of the process are illustrated in this case study. There are few resources available in the market for underwater excavation of weld defects other than manual grinding or bespoke milling tools. Manual grinding is time consuming, labour intensive with the risk of not fully excavating the defect and can be considered more hazardous for the diver, while milling tools are expensive, long-lead and limited in their application. In comparison to mechanical as well as thermal cutting methods, the Hydro-Carbon Arc Gouging technique proved extremely effective. The process has a high degree of control, improved quality, increased safety and speed—producing in a half a million-pound cost savings for the project. |