Hydrogen Assisted Cracking Failures of Girth Welds in Oil and Gas Pipelines

There are more than 2.5 million miles of oil and gas pipelines in the United States, totaling over 330 million girth welds below ground. During construction, girth welds are susceptible to the formation of various defects, one of which is hydrogen-assisted cracks. The synergistic impact of tensile stress, a susceptible microstructure, and atomic hydrogen can lead to hydrogen embrittlement and the formation of hydrogen cracks. This paper reviews hydrogen cracking of girth welds in carbon steel pipelines made during new construction and provides examples involving hydrogen cracking in which failure analysis techniques were used to establish the metallurgical cause of failure.