Session: 05-01-1: Materials and Joining - High-strength Line Pipe

Paper Number: 133729

133729 - 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 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 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.  

The method consists of developing optimal statistical distributions for the toughness values with respective populations grouped by grade (API 5L Grade X52 Pipe, API 5L Grade X60 Pipe and higher strength pipe materials).  A conservative default toughness value is then selected based on the optimal distribution and recommended percentile and confidence level.

Statistical tests were then performed among sub-populations of each grade (based on wall thickness, diameter, and decade of installation) with these statistical tests concluding that there is no meaningful difference between the sub-populations and the larger dataset (within a defined confidence level).

Results were summarized and submitted in a notification to the governing regulatory agency.  After several questions and calls to present the technical merit, subsequent approval and “no objection” was granted to both pipeline operators.

Presenting Author: Jose Molina Structural Integrity Associates Inc.

Presenting Author Biography: Jose Molina is an engineer with ten years of experience in the oil and gas industry. Jose earned his Bachelor of Science degree in Petroleum Engineering, graduate certificate, and Master of Science degree in Data Science from Colorado School of Mines. He developed advanced petrophysical models for reservoir characterization analyzing well logs, geo-mechanical properties, and core analysis. Jose also has proven expertise in building data-intensive applications and predictive modeling delivering valuable insights via data analytics and advanced statistical methods.

Authors:

Scott Riccardella Structural Integrity Associates, Inc.
Zain Al-Hasani TC Energy
Sean Moran Williams
Dan Ostahowski Williams
Jose Molina Structural Integrity Associates Inc.
Clifford Maier TC Energy