Slow Strain Rate Testing for Materials Evaluation in High-Pressure H₂S Environments^☆

Traditional environmental cracking test methods such as the NACE tensile test or the MgCl₂ test have limitations for extreme sour service materials evaluation. The slow strain rate test (SSRT) method overcomes many of the disadvantages of more traditional test methods, while still posing some unique questions of its own. Apparatus and procedure are described. Selection of appropriate strain rate and sample size are discussed. Evaluation criteria are compared, including time to failure, percent reduction in area, loss of ductile fracture surface area, and the appearance of secondary cracking. Certain ambiguous features in the transition zones between cracking and noncracking environments are described. The strengths of the method (rapidity, positive results) are compared against its limits of use.