Deepwater Welding for Installation and Repair -- A Viable Technology?

摘要

Arc welding is routinely employed for underwater installations and repairs, with the majority of operations involving manual welding, although the use of semi-automated equipment is well established. Welding process consistency and reliability remain matters of some concern and the occasionally direct human intervention is necessary, even in relatively shallow waters. This paper focuses on the potential advantages and drawbacks of arc welding for deepwater applications where direct human intervention is not possible. The results of recent studies have demonstrated the surprisingly robust nature of arc welding processes at water depths to 2,500m (8,200ft). Novel process control methodologies have been successfully employed to minimise instabilities under essentially turbulent conditions. Results from recent welding trials in the UK are presented and the influence of enhanced cooling on materials performance is outlined. Welds performed include positional linear butt joints and orbital welds on API 5L X65, API 5L X70 and supermartensitic pipeline steels. The welding function represents only one aspect of a deepwater operation. Consideration is also given to the associated engineering problems that must be addressed in order to provide a viable technological solution for deep water applications. A more flexible approach to engineering solutions is likely to result in cost effective developments for future deepwater joining needs.