Digital Repository, ICF12, Ottawa 2009

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In-Situ Monitoring of Hydrogen Embrittlement in Ferritic Steel Pipelines
F. M. Haggag

Last modified: 2013-05-07


The Stress-Strain Microprobe® (SSM) system that utilizes an in-situ nondestructive Automated Ball Indentation (ABI) test technique was used to monitor the changes in tensile and fracture toughness properties of hydrogen transmission pipeline steels. Fracture toughness was calculated from integration of the ball indentation/deformation energy as a function of depth up to a critical depth. The latter depends on the critical fracture stress at the test temperature.
ATC’s innovative hydrogen pressure chamber allows simultaneous exposure of six pipeline steels, and multiple ABI tests were performed on each disc at various times. The ABI-determined fracture toughness of X80 pipeline steel decreased by 12%, 25%, 32%, and 30% after 13.79 MPa (2,000-psi) hydrogen exposure times of 5, 25, 100, and 200 hours. The reduction in fracture toughness saturated at 100 hour for the 9.5-mm thick sample while the increase in tensile properties was very small for the X80 steel. No hydrogen embrittlement was detected for the other pipeline grades tested in this project.

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