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Corrosion occurs in the high-temperature and high-pressure hydrogen-containing equipment and pipelines in hydrofining, hydrocracking, and catalytic reforming units, with corrosion forms including surface decarburization and internal decarburization (hydrogen corrosion). These corrosions occur in carbon steel, C-0.5Mo steel, and chrome-molybdenum steel. Carbon in steel migrates to the surface at high temperatures, where it forms the gaseous carbon compound CH4 or CO2 in an oxygen-containing environment. Steam accelerates this reaction. Hydrogen under high temperature and pressure diffuses into the steel and reacts with unstable carbides to produce methane gas. This methane cannot escape from the steel, so it accumulates at grain boundaries or inclusions, resulting in high stress that ultimately leads to cracks, causing the steel to crack or the metal to bulge. When steel contains segregated impurities, strip-like inclusions, or stratification, the accumulation of methane in these areas can lead to severe bubbling. The solubility of hydrogen in austenitic steel is one order of magnitude higher than that in ferritic steel, whereas the diffusion coefficient of hydrogen is about two orders of magnitude lower in austenitic steel compared to ferritic steel. Therefore, the use of a stainless steel composite surfacing layer can reduce the impact of hydrogen partial pressure on the base material.