Test Methods for Evaluation of Materials for Wet H2S Service

Tang, Henry (InterCorr International Inc) | Cayard, Michael S. (InterCorr International Inc)


Two of the most common corrosion problems encountered in wet H2Sservice are sulfide stress cracking (SSC) and hydrogen-induced cracking (HIC). The problems related to SSC were first recognized in the late 1940s and early 1950s. The interest in SSC was vastly increased after the tubing failure at Pincher Creek field in Alberta, Canada in 1949 and the well blowout at France?s Lacq field following the failure of the drill pipe and casing in 1951. Following a series of sour service pipeline failures in the Middle East in 1972 to 1974, the effect of HIC also caught the attention of the industry~. Since then, effort has been made to combat these problems by researching the mechanism related to SSC and HIC and methods to improve materials resistance to such damage. Test methods such as NACE Standard TMO177 [1] and TM0284 [2], were developed and standardized by NACE to facilitate the process of evaluating and testing material for wet H2Sservice. These two standards provide a solid base for developing testing and research programs for materials evaluation and are two of the most widely used standards for sour service qualification. In order to filly utilize these standards, understanding of the corrosion and cracking mechanism and the usage of the standards are important. This paper attempts to address these issues and will discuss the background theories, proper usage, and limitation of the standards. In addition~ intiormation will be given on typical acceptance criteria in terms of linking test results to field applications.

In this paper, two types of hydrogen related damage on material related to wet HJ3 service environment and their corresponding standard test methods will be discussed. The two types of damage are sulfide stress cracking (SSC) and hydrogen-induced cracking (HIC). NACE Standard TMO177, Laboratory Testing of Metals for Resistance to Specific Forms of Environmental Cracking in H2S Environment, was developed to facilitate conformity in testing of SSC so that data from different sources could be compared on a common basis. The Standard was first developed by Task group committee T-IF-9 in 1977, and the latest version was revised and released in 1996. NACE Standard TM0284, Evaluation of Pipeline and Pressure Vessel Steels for Resistance to Hydrogen-Induced Cracking was developed to evaluate the resistance of pipeline and plate steels to hydrogen-induced-cracking (HIC) and to provide a reliable test method for comparison of test data from different laboratories. This Standard was developed by task group T-lF-20 in 1984 and was last revised in 1996. Discussion in this paper will be based on the latest version of both standards. The following sections will discuss the background and theories of both SSC and HIC, the contents, proper usage, and some of the limitations of the Standards, and summarizes some of the acceptance criteria used in the industry.