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<p>The welded joints exhibit a higher susceptibility to premature failure compared to the base metal in specific segments of shale gas gathering pipelines. However, the underlying mechanism remains unclear. This study combined field failure analysis, electrochemical tests, and multiphysics modeling to elucidate this failure mechanism. The results reveal that a significant potential difference of approximately 34&#xa0;mV between the weld metal (anode) and the base metal (cathode) drives macroscopic galvanic corrosion. The CO<sub>2</sub>-saturated environment further accelerates this process, resulting in an average corrosion rate at the weld that is 1.5 times that of the base metal, with localized peak rates reaching 3.6 times higher. The developed multiphysics model successfully replicated the localized damage morphology observed in the field and predicted a maximum corrosion depth of 157&#xa0;μm at the weld after 16&#xa0;years of service, thereby confirming the mechanism. This work clarifies the dominant role of macro-galvanic corrosion and indicates that pipeline integrity management strategies must shift from uniform corrosion control to the targeted inhibition of localized galvanic corrosion at welds.</p>

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Macro-Galvanic Corrosion and Failure Evaluation of Shale Gas Pipeline Welds in CO2 Environment

  • 期刊论文

  • 发表日期：

    2026年1月29日

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  • Kun Hu,
  • Ziyi Liu,
  • Yong Chen,
  • Taiwei Luo,
  • Haijun Tang,
  • Yuancheng Wei

摘要

The welded joints exhibit a higher susceptibility to premature failure compared to the base metal in specific segments of shale gas gathering pipelines. However, the underlying mechanism remains unclear. This study combined field failure analysis, electrochemical tests, and multiphysics modeling to elucidate this failure mechanism. The results reveal that a significant potential difference of approximately 34 mV between the weld metal (anode) and the base metal (cathode) drives macroscopic galvanic corrosion. The CO2-saturated environment further accelerates this process, resulting in an average corrosion rate at the weld that is 1.5 times that of the base metal, with localized peak rates reaching 3.6 times higher. The developed multiphysics model successfully replicated the localized damage morphology observed in the field and predicted a maximum corrosion depth of 157 μm at the weld after 16 years of service, thereby confirming the mechanism. This work clarifies the dominant role of macro-galvanic corrosion and indicates that pipeline integrity management strategies must shift from uniform corrosion control to the targeted inhibition of localized galvanic corrosion at welds.