Further Analysis on M13Cr-110 NACE TM0177 Method A Test Acceptability Prediction

Martensitic stainless steels continue to be one of the most widely used corrosion resistant alloys in oil and gas developments. Determining if a martensitic stainless steel is acceptable in an unproven environment requires testing to confirm, but predicting the outcome of a given test environment is often initially based on personal experience rather than a qualitative assessment. An empirical method for improving the predictability of NACE TM 0177 Method A Tensile tests on modified 13Cr 110 ksi grade martensitic stainless steels based on an H₂S/Chloride/pH function has previously been developed based on published data in order to address this uncertainty. The environments considered by this function are only limited by the capabilities of the NACE Method A test, and provide a method for rapidly estimating if a M13Cr 110ksi grade should pass or fail in multiple different environments. As a follow-on to the development of this empirical method, data points from new tests were used to check the general predictability of the H₂S/Chloride/pH function. The general function was modified due to the addition of the new data, and subsequently checked again against a separate set of data. The nature and implications of these findings are discussed and conclusions drawn regarding the performance and value of the methodology for the evaluation of future materials applications.

Keywords: Modified 13Cr, SSC, Martensitic stainless steel, Sour service, NACE Method A Test