Stress corrosion testing of welded supermartensitic stainless steels for oil and gas pipelines

Abstract

Qualification tests with respect to stress corrosion cracking and sulphide stress corrosion cracking of welded pipeline for oil and gas transmission are often based on four-point bend testing. However, there are no reliable standards or guidelines that account for the range of variables that may affect the results, including root profile, specimen thickness, non-uniform thickness associated with ‘stepped’ welds, test configuration (fixed or rotating loading carriage), use of tensile or flexural data to set strain levels, and the temperature dependence of material properties when testing. An investigation of the significance of these factors for stress corrosion testing has been undertaken for a supermartensitic stainless steel. In addition, specific stress corrosion cracking tests in a simulated production fluid are also reported and complementary electrochemical tests are discussed.