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Topic: What metal should be used to fabricate a storage tank for 98% sulfuric acid?

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What metal should be used to fabricate a storage tank for 98% sulfuric acid? I have heard that mild steel would be acceptable.  Is mild steel okay for storage of 98% sulfuric acid  at  45 to 50 °C? 
  • Avatar Brian Dalder Forum Moderator 177 Posts

    Re: What metal should be used to fabricate a storage tank for 98% sulfuric acid?

    Sulfuric acid is a tricky chemical to deal with since its corrosivity varies with concentration, temperature, impurities, and velocity; sometimes in unexpected ways. According to MTI Publication 1: Materials Selector for Hazardous Chemicals: Sulfuric Acid, glass-lined steel or a high-silicon stainless steel would work. You may want to get further and more detailed guidance from one of the many references and standards published on this subject.

  • Re: What metal should be used to fabricate a storage tank for 98% sulfuric acid?

    anonymous
    Having designed a couple of 98% sulfuric acid off-loading and storage systems, I learned that the question is much more complex. I recommend first studying the issues related to the concentrated acid, then get as good an understanding of the use, rate of consumption, siting issues, etc., that you can. Mild CS can work fine. Kynar might be the right way to go. But there is no standard answer. One good and readily available reference is http://www.sulphuric-acid.com/techmanual/Storage/storagetanks.htm
  • Avatar Konstantinos Kalaitzoglou Community Member 2 Posts

    Re: What metal should be used to fabricate a storage tank for 98% sulfuric acid?

    Last edited: 12 January 2015 at 6:05am
    Not being a corrosion expert, I worked in Phosphoric acid Operations of a fertilizer plant (1976-9) with sulfuric acid tanks near by (93% or 98% w/w, capacity higher than 500 m3 each, temperature from ambient to estimated 50 oC). All these tanks were made of carbon steel without lining. Wall thickness was measured in regular basis, yet once a very low value was detected in one tank (but before leakage). . Air through tank inbreathers was not being dried, even though this would add to safety. Data sheet of a refinery sulfuric acid tank (~93% acid, carbon steel, 2011) used desiccant for this reason. Air humidity can dilute the acid locally and then it gets corrosive. In the fertilizer plant, a serious acid leakage through a pipe occurred after one humid night, for a carbon steel blind joint was totally corroded. . Above reference by anonymous advises carbon steel grades. Fertilizers do not need very pure acid, otherwise glass lined steel or other materials have to be used (no experience).