Dry Hyperbaric Welding of Subsea Pipelines in the North Sea

The expansion of the oil fields in the North Sea has been a driving force for technology development of remotely controlled hyperbaric welding of subsea pipelines, which has been used for tie-ins and repair of pipelines since the mid-1980s. SINTEF (research institute in Norway) has been involved in the technology development from the early 1970s, and has been a long-term supplier to the pipeline repair system (PRS) pool, headed by Statoil. SINTEF has laboratory facilities for mechanized hyperbaric welding, and has been involved in the development of equipment, in addition to being responsible for the development and qualification of all the welding procedures used by Statoil and Hydro with the PRS system. Presented here is an overview of the technology for hyperbaric welding of pipelines with the PRS system, with main focus on the welding process and procedures.