Rapid corrosion occurs on many materials exposed to highly oxidizing mineral acids, such as concentrated sulfuric and nitric acids. Alloy 33 (UNS R20033) was specifically developed to have excellent corrosion resistant in these types of highly oxidizing acid environments. The corrosion resistance of Alloy 33 is attributed to its high chromium content of 33%, which is several percentage points higher than commercial alloys available only a few years ago. The high chromium concentration is the key feature that gives the benefit of excellent corrosion resistance to highly oxidizing mineral acids. Alloy 33 can be used in many applications where alloys with lower chromium contents simply will not work. Examples of such applications include production of concentrated sulfuric and nitric acids, pickling tanks with mixtures of nitric and hydrofluoric acids, and processing of nuclear materials in nitric hydrofluoric mixtures. Corrosion data and field experience show that Alloy 33 is typically the strongest candidate for applications involving highly oxidizing mineral acids.

Subject
Acids, Materials, Corrosion resistant alloys, Stainless alloys, Corrosion rate, Sulfuric acid, Nickel based alloys, Molybdenum alloys, Commercial alloys, Nitric acid, Hydrofluoric acid, Corrosion resistance, Stainless steel
Keywords:
alloy 33, corrosion, sulfuric acid, nitric acid, hydrofluoric acid, alkaline solutions
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2004
Association for Materials Protection and Performance (AMPP)
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