The proper MOC for a phosphoric acid storage tank will depend on its purity and in particular, the concentrations of halides such as chlorides, and fluorides. Recommended materials of construction for a refined product storage tank would be fiberglass reinforced plastic, rubber-lined mild steel (like you probably have already), 316L stainless steel, polypropylene, and polyethylene. Of course not all of these materials may be suitable for a tank as large as yours. For more detailed information you should consult a reference text such as "Materials Selector for Hazardous Chemicals, Vol. MS-7: Phosphoric Acid," published by MTI.
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Konstantinos Kalaitzoglou Community Member 2 Posts
Re: What is the proper MOC for a phosphoric acid storage tank?13 November 2014 at 10:34am Last edited: 13 November 2014 at 3:40pmNot being a material expert, I think I can give some additional information to the above (mainly concerning application to fertilizers), since I worked in the operations of a phosphoric acid plant (treating phosphates) in 1976-1979. For mentioned tank size (3000 m3), only rubber lined tanks were considered economical, and I believe this is also true today. At that time Glass Reinforced Plastic tanks could be used for capacities up to (say) 200 m3 and 316 L tanks (or of similar grade) for much lower sizes. In 1964 "lead cladded" tanks (400 m3 each) were erected, which had many maintenance troubles and went out of service in early 1980s. For the mentioned rubber-lined tanks (30% or 50% P2O5, open, vertically agitated, max liq temp about 60 oC) no excessive maintenance problems were encountered. It is however noted that rubber lining needs to be implemented by a contractor of proven experience; and sandblasting of tank internal steel walls should be "meticulous".