Innovative Duplex Stainless Steel UNS S83072: Enhanced Strength for Deep-Sea Umbilical Tubing

Abstract UNS S83072 is a newly developed super duplex alloy with additions of W, Mo and N. Cold pilgered and annealed seamless tubes in UNS S83072 have been produced in three umbilical dimensions (½”, ¾”, 1”), and laboratory testing has provided mechanical properties and corrosion resistance to pitting and chloride stress corrosion cracking (Cl-SCC). The development of a unique filler metal has run in parallel and a qualification according to ISO 15792-1 has been submitted. The new filler metal UNS S83072 generates welds of high integrity, free of detrimental precipitates and good ductility. The all-weld metal has mechanical and corrosion properties that is on par or exceeds that of the base-metal. Investigations that were performed on seamless tubes and butt welded joints, have shown that UNS S83072 has a very high strength and excellent corrosion resistance, making the grade ideal for the umbilical application, both when it comes to deeper and more challenging environments, and also as a cost-efficient alternative with several design advantages.