The concentration of diffusible hydrogen introduced into steel, fatigue crack growth rates and fatigue lives were determined in sour crude oil containing a high concentration of hydrogen sulfide and under electrolytic hydrogencharging conditions in neutral solution, using a TMCP high strength steel and a mild steel which are used for ship hull plates. The experimental results demonstrated that the concentration of diffusible hydrogen absorbed into steel was less than 0.1ppm in sour crude oil under atmospheric pressure, and such a small amount of hydrogen accelerated the fatigue crack growth in the high ΔK regime and shortened the fatigue life in the high stress range region, but did not shorten the fatigue life in the low stress region. The electrolytic hydrogen-charging condition appeared to be appropriate as a fatigue-crack-growth test environment to simulate sour crude oil. The deterioration of fatigue characteristics of the TMCP high strength steel was similar to that of the mild steel.
