Safety evaluation of high pressure vessel under corrosive and fatigue environment of sulfureted hydrogen

Fatigue crack growth rate da/dN of the material 4130X steel, which is used to manufacture the high-pressure vessel, in moderate concentration (200 x 10(-6)) sulfureted hydrogen solution is studied experimentally. The equation of fatigue crack growth rate is found according to the experimental data by using Paris expression. Fatigue crack growth rate equation of 90% reliability and 90% believability is also found taking into account experimental randomicity. By using inverse inferring method, allowable crack sizes with variable crack shape are determined in certain setting inspection period to assure the safety of the vessel. And the relationship between allowable crack depth and original crack length is obtained and shown with figures which are very convenient for engineers in evaluating residual life of the pressure vessel.