Sulfuric acid is tricky to deal with because its corrosive properties change dramatically with velocity, concentration, impurities, and temperature. Interestingly, 98% sulfuric acid is less corrosive than 93% and both are less corrosive than intermediate sulfuric acid concentrations. Due to velocity effects and other considerations, the proper MOCs for sulfuric acid might be different depending on the equipment (e.g., storage tank, piping, pumps, valves, etc.). In general, for 98% sulfuric acid, carbon steel tanks with stainless steel clad or overlaid nozzles are used for storage and 304L and/or 316L stainless steel are used for piping. The details of design, fabrication, construction, inspection, and maintenance of sulfuric acid and oleum storage tanks and piping systems are contained in numerous documents and books based on many years of experience in the field. Two that I am familiar with are NACE standard SP0294 "Design, Fabrication, and Inspection of Storage Tank Systems for Concentrated Fresh and Process Sulfuric Acid and Oleum at Ambient Temperatures" and "Materials Selector for Hazardous Chemicals, Vol. 1: Sulfuric Acid, 2nd Edition" published by MTI. I suggest you obtain copies of one or more of these publications to get more comprehensive answers to your question.
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