| In oil refinery and petro-chemical industry, key equipment-hydrogenation reactor operates in harsh conditions. It operates in high pressure condition, and in the presence of high pressure hydrogen. Fluctuation of temperature and pressure in the course of operation, and variation of temperature and pressure during start operation and shutdown will cause stress cycle fatigue, crack initiation and fatigue propagation of already existing defect. As to 2.25CrlMo, the most widely used steel of hydrogenation reactor, low cycle fatigue and fatigue propagation test were conducted at room temperature and elevated temperature to comprehensively investigate low cycle fatigue behavior and fatigue crack propagation regularity. Low cycle design curve, fatigue crack growth rate equation and damage mechanics model for life prediction were obtained. The main contents are as follows:Based on low cycle fatigue test under total strain control at room temperature, cycle stress-stain relation, strain-life relation and dummy stress amplitude-life relation were obtained. Low cycle fatigue design curve of 2.25CrlMo were established after correction for mean stress and application of stress safety factor and life safety factor in accordance with ASME code. The design curve was compared with the curve of ASME code and the curve of BS5500 code, and basis for anti-fatigue design of hydrogenation reactor was provided.On the basis of review on damage theory research and progress on application of damage mechanics to fatigue research, a new exhaustion potential model was proposed. Total stress amplitude was used to define damage variable, damage progressing equation for low fatigue was obtained. The equation was perfectly good compared with test result. These are elementary exploration for application of damage mechanics to fatigue life prediction of hydrogenation reactor.Through analysis of fatigue test result under stress control at 350 and 420 癈, stress life curves at two temperature were obtained. After mean stress correction and introduction of safety factor in accordance with ASME code, fatigue design curves at two temperatures were gained, and the curvesIIIwere compared with ASME design curve.Fatigue crack growth test was conducted at room temperature and elevated temperature. Paris equations for fatigue crack growth rate at various temperatures were obtained. After analysis of temperature effect on fatigue crack growth rate, temperature factor was put forward. Formula considering temperature effect for fatigue crack growth rate was reached. Basis for crack growth calculation under cycling load of hydrogenation reactor was provided.Microscopic analysis for fracture surface of crack growth specimens at various temperatures was conducted. Microscopic characteristic of fatigue crack growth at various temperatures was preliminarily investigated. At last, research result in the paper was used to estimate crack growth of an in-service hydrogenation reactor. The safety status of the equipment was analyzed, proposal for safety operation was put forward.In conclusion, correction of formula put forward by Zheng Xiulin was conducted. The corrected formula was used to obtain stress life curve of 2.25CrlMo steel at 350 and 420 ,. Low cycle design curve at 350 and 420 was established. Important basis was provided for formation of fatigue design method of hydrogenation reactor operating at 350-420. Based on fatigue crack growth test result at various temperatures, temperature effect was considered and temperature factor was put forward to obtain fatigue crack growth rate equation taking temperature effect into account. A sort of exhaustion potential model was suggested, and low cycle damage evolving equation was obtained on the basis of the exhaustion potential. Preliminary exploration was conducted for damage mechanics to be used to life prediction for hydrogenation reactor..
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