Evaluation of Selective Seam Weld Corrosion Susceptibility

Abstract Selective seam weld corrosion (SSWC) in autogenous welds is characterized by accelerated corrosion of or near the bondline which results in a groove-like feature that often coincides with shallower corrosion that can extend beyond the width of the longitudinal seam. Historically, SSWC has been referred to as “grooving corrosion”, “knife-line attack”, or “trench-like corrosion”. In 2021, the Pipeline Research Council International, Inc. (PRCI) funded a project, PRCI Project EC-2-12, to evaluate SSWC as a threat to gas and liquid pipeline systems. The project included a literature review of key parameters influencing the likelihood of SSWC within a particular type of pipe over others, benchmarking of the key parameters using industry experience and data, and the development of a susceptibility process for the threat of SSWC within gas and liquid pipeline segments. From the literature review, a summary of hypothesized influencing parameters was compiled and those considered more strongly and consistently indicative of susceptibility were identified as key parameters (e.g., longitudinal seam weld type, chemical composition of the plate material, and evidence of a post-weld heat treatment, etc.). The key parameters were then benchmarked against pipeline industry data from confidential as well as public sources. Industry data were collected for line pipe known to be susceptible to the threat of SSWC (i.e., SSWC has been identified within it through direct examination and/or metallurgical analysis). Additionally, mill test reports for line pipe manufactured prior to 1990 and historical line pipe manufacturing specifications that could indicate typical manufacturing practices of the time were collected and compiled. As a result of the benchmarking effort, some key parameters were confirmed, and others were dismissed if industry data indicated it was unlikely they could be relied upon to determine susceptibility to the threat of SSWC individually or in concert with other parameters. Key parameters that were confirmed as reliable through industry benchmarking and considered readily accessible to most pipeline operators were leveraged in the development of a susceptibility framework. The following paper details the sources identified as a result of a comprehensive literature review, the SSWC susceptibility parameters with industry consensus, the SSWC susceptibility parameters determined to be reliable as a result of a benchmarking study, and a SSWC susceptibility framework that can be used to categorize and prioritize segments for a baseline assessment relative to the threat of SSWC.