Method for Establishing a Default Toughness for DSAW Long Seam Welds

Abstract Double Submerged Arc Welded (DSAW) longitudinal seam welds have typically experienced fewer failures and demonstrated a greater level of reliability than other seam weld types (such as vintage Electric Resistance Welded (ERW) pipe). Given the greater reliability of DSAW seam welds, a higher default toughness is warranted when evaluating pipeline defects. This paper provides a comprehensive review of two pipeline operators’ systems, demonstrating that improved pipe manufacturing techniques such as DSAW pipe have significantly higher Charpy V-Notch (CVN) impact energy values for the longitudinal seam weld metal and heat affected zone than the default values prescribed in 49 CFR 192 to be used for all seam weld types. In accordance with pipeline safety regulation, these operators have proposed to use alternative, but conservative, default toughness values when performing Predicted Failure Pressure (PFP) analyses of crack or crack-like defects in DSAW long seam welds. This paper provides a summary of the results of the systemwide review for two major North American pipeline operators and details the process used to complete the statistical analysis to develop alternative default toughness values for DSAW seam welds.