Session: MF-02-01 Materials for Hydrogen Service (Joint with CS-02 and HT-07) - Evaluating Component Life

Paper Number: 105791

105791 - Crack Growth Retardation and Hydrogen Sensitivity in Pipeline Steels 

Over a five-year period, a series of fatigue crack growth experiments have been conducted in air and in a bubbling CO₂ environment to induce free hydrogen ingress. While the main objective of the hydrogen-charging research targeted characterization of near-neutral stress corrosion crack growth, many of the findings can inform emerging hydrogen transport crack threat management. Summarizing and highlighting these findings and trends could benefit the pipeline industry and accelerate research toward international net zero carbon objectives.

Crack growth retardation in X52 and X65 were found to be readily achieved with an overload cycle, both in air and with hydrogen charging. Subsequent underload cycles were shown to cause resumption of crack advancement: such underload cycles are typical of pipeline operations. Grade X65 pipe steel samples with hydrogen charging were found to be sensitive to underload cycles with significantly higher da/dN growth rates and an observed lower ΔK threshold after such underload cycle events.

Crack retardation models currently available were evaluated using the AFGROW^TM crack growth modeling software to determine and compare model performance to test results. Potential implications of these findings to mainline pipe integrity management are considered in light of crack threat management methods, specifically periodic hydrostatic test methodologies, including emerging hydrogen transport considerations.

Presenting Author: Sanjay Tiku BMT Global Canada

Presenting Author Biography: With more than 35 years of experience in fracture, fatigue, structural design, stress and loads analysis, testing, and incident investigation, Lyndon now fills the role of Cracking Threat Subject Matter Expert at Enbridge Liquids Pipelines. Lyndon holds a bachelor of science degree in Mechanical Engineering and two Masters degrees: Aeronautical Engineering and Secondary Education, and was employed in the aerospace industry at Boeing for 30 years. Employed at Enbridge since 2016, Lyndon is a Professional Engineer in the province of Alberta, Canada, holds eight US Patents, and is heavily involved in advancing pipeline integrity science.

Authors:

Sanjay Tiku BMT Global Canada
Lyndon Lamborn Enbridge LP
Greg Nelson University of Alberta
Olayinka Tehinse Stantec