Hydrogen-Induced Cracking (HIC)

In oil and gas industry, pipeline for natural gas transportation is exposed to wet H₂S environments (sour environments) in some cases. The presence of H₂S in the sour environment enhances hydrogen entry into the steel as a result of catalytic action of H₂S. Absorbed hydrogen atoms in the steel diffuse and accumulate in a local area and finally cause several types of environmental cracking such as hydrogen-induced cracking (HIC), sulfide stress cracking (SSC), and stress oriented hydrogen-induced cracking. HIC is one of the major issues of line pipe exposed to sour environments. There are some guidelines on materials requirements for carbon and low alloy steels for H₂S-containing environments in oil and gas production. In general, HIC susceptibility, such as crack sensitivity ratio (CSR), crack length ratio (CLR), and crack area ratio (CAR), is evaluated after the test duration, typically 96 hours, in accordance with NACE Standard TM0284-2016.