Trends in welding of offshore flowlines and pipelines

During the last 10 to 15 years, the Norwegian energy company Statoil has qualified and gained welding and materials technology experience with a wide range of new linepipe materials like supermartensitic stainless steels, metallurgically or mechanically bonded CRA(Corrosion Resistant Alloy)- clad (316L, alloy 825), as well as different types of conventional carbon steel materials (SAWL, seamless, HFW). Some challenges and practices in terms of weld fabrication, non-destructive testing (NDT) and adequate weld property relationships will be presented in this article, both for S-laid and reeled pipelines. For the last 25 years, Statoil has also performed a substantial amount of subsea tieins using hyperbaric welding and this article will also present the current trends and challenges for this welding method.