Slow Strain Rate Test Method for Screening Corrosion-Resistant Alloys (CRAs) for Stress Corrosion Cracking in Sour Oilfield Service

Failures of metals exposed to hydrogen sulfide (H₂S)-containing (sour) oilfield production environments have been reported for more than 45 years and have usually occurred in carbon or low-alloy steels. Failures of high-strength steels by brittle cracking (sulfide stress cracking [SSC]) and of lower-strength plate and pipe steels by blistering and hydrogen-induced (stepwise) cracking have also been reported. As a result, engineers and scientists have developed test methods to evaluate steels for resistance to failure by these mechanisms in sour environments. These and other considerations led to the establishment of NACE Task Group T-1 F-9 on Metallic Materials Testing Techniques for Sulfide Corrosion Cracking, which developed NACE Standard TM0177 in 1977. The task group has continued to revise that standard. This standard establishes a SSR test method for screening CRA materials (i.e., stainless steels and nickel-base alloys) for resistance to SCC at elevated temperatures in sour oilfield production environments. The fact that this test method is a screening method implies that further evaluation or additional experience may be required before materials selection decisions can be made.