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Determining Steel Weld Qualification and Performance for Hydrogen Pipelines: Phase I Report



Matthew Connolly, May Ling Martin, Zack Buck, Newell Moser, Enrico Lucon, Damian Lauria, Peter Bradley, Andrew Slifka, Robert Amaro


This report details the results of Phase I of the DOT/PHMSA sponsored work on "Determining Steel Weld Qualification and Performance for Hydrogen Pipelines". In this work, the goals of Phase I were 1) to perform a literature review of steel weld qualification and performance for hydrogen pipelines, 2) to form a committee of industry and subject matter experts, 3) to review the current codes and standards related to pipeline steel welds, 4) to review the regulatory requirements and limits for materials under 49 CFR Part 192, and 5) to identify materials necessary to inform advancement of 1-4. A research plan was developed that takes a three-pronged approach to determining weld and HAZ performance for hydrogen pipelines: 1) survey industry for a wide spectrum of typical pipeline welds, 2) use Gleeble to simulate HAZ microstructures, and 3) systematically study standard and exploratory weld filler materials. During Phase II, NIST will perform Charpy impact tests, fracture toughness tests in air, in hydrogen gas, and in hydrogen/methane blends, hardness mapping, and microstructure characterization over a wide range of welds and HAZs. Material procurement was begun through connections formed through the committee of subject matter experts and others within API 1104. At the submission of this Phase I report, NIST has procured ten pipes with welds formed using filler materials and six pipes with welds formed without filler materials. Additionally, NIST has formed collaborations with the Colorado School of Mines to perform Gleeble welding simulations as well as mechanized welding using a range of filler materials.
PHMSA Research and Development Program


SME B31.12, 49 CFR Part 192, Hydrogen-assisted cracking, hydrogen embrittlement, fracture, Charpy, fatigue, fatigue crack growth rate, microstructure, pipeline steel.


Connolly, M. , Martin, M. , Buck, Z. , Moser, N. , Lucon, E. , Lauria, D. , Bradley, P. , Slifka, A. and Amaro, R. (2023), Determining Steel Weld Qualification and Performance for Hydrogen Pipelines: Phase I Report, PHMSA Research and Development Program, [online],, (Accessed May 21, 2024)


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Created May 23, 2023, Updated July 4, 2023