Hydrogen Induced Cracking (HIC) is a major issue of the linepipe exposed to sour environment. NACE MR0175 / ISO15156 classifies the severity of sour conditions as a function of pH and H2S partial pressure, based on Sulfide Stress Cracking (SSC) susceptibility of low carbon steel from experiments. Recently, the sour environmental severity diagrams for HIC and SSC were proposed based on the equal hydrogen concentration concept. From this concept, HIC behavior corresponds well with the steady-state hydrogen permeability, while SSC behavior is close related to the maximum hydrogen permeability. In this study, HIC behavior was closely investigated using the phased-array ultrasonic testing techniques to create three-dimensional (3D) images of cracks. HIC initiation and propagation behaviors were clearly visualized and investigated. It was found that HIC susceptibility was strongly affected by the hydrogen diffusion and corresponded with the steady value of hydrogen permeability.

Subject
Hydrogen induced cracking, Hydrogen permeation, Hydrogen concentration, Diffusion, Permeability, Sour environments, Crack initiation, Partial pressures, Sodium chloride solution, Steel, Hydrophobic interaction chromatography, Sulfide stress cracking, Hydrogen
Keywords:
sour environment, HIC, hydrogen permeability, in-situ, ultrasonic inspection, linepipe
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2021
Association for Materials Protection and Performance (AMPP)
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