Parent material and weldment degradation of vessels caused by fatigue, vibration and hydrogen attack

Six installed Reduction Reactors showed the same failure pattern, which can be attributed to inadequate original design, material degradation due to service conditions and improper maintenance activities. The paper describes steps taken to establish the feasibility of restoring the vessels to reliable operation by suitable program-mes of repair. Successful repairs have been achieved through metallurgical studies, fitness for purpose evaluations, remaining life assessment, re-design and recommendation for future field inspections.