Corrosion of lined steel pressure equipment in aqueous H2SO4 service in a water treatment plant

This paper details corrosion that occurred in two identical process pressure vessels during the first 4 years of operation. Corrosion occurred at branch nozzles, shell sections and structural attachments, which resulted in unplanned shutdowns and subsequent repairs. In situ vessel modifications were completed in order to reduce the number and frequency of corrosion sites. Design and fabrication considerations that should be assessed in detail during the initial design phase are presented. Issues that can increase the shutdown frequency while decreasing availability and the inspection interval are discussed. Recommendations are made that are intended to alert designers, fabricators, owner/operators and inspectors to fundamental issues associated with lined steel pressure equipment to be considered where such equipment is proposed in a corrosive process environment.