An Update on the Use of Duplex Stainless Steels in Sour Environments

摘要

Since the early days of production of the Lacq sour field in the South West of France, where early duplex stainless steel grades were used on wellheads and valves these alloys have been used extensively in the upstream Oil and Gas industry for sour applications. It is known that these alloys have a limited resistance in H_2S containing production environments as given in the NACE MR0175/ISO 15156 Standard. However these limits are conservative because they consider a low pH and high chloride content at the same time, a situation rarely encountered in service. Temperature is an additional parameter with a complex influence which may depend on the other parameters. This topic is not new and several literature reviews have already been published on this subject over the years. Unlike these past reviews this paper aims at summarizing the sulfide stress cracking and stress corrosion cracking resistance of commonly used duplex stainless steels in sour media under more relevant and realistic operating conditions. The goal is to give an overview of the latest available knowledge on the subject including selected relevant literature data, service experience and new laboratory data.