Expert ForumsCorrosion

Topic: Re: What's the best material for use with carbonic and sulfuric acid?

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It wasn’t clear whether you have a mixture of dilute sulfuric acid and carbonic acid or will be handling these acids separately in the same equipment. In either case, a place to start is to look up compatibility data for the individual components. A quick check of Schweitzer’s Corrosion Resistance Tables rates 316L stainless steel as “good” with carbonic acid up to 175  degrees C. However, “good” is a corrosion rate of < 20 mpy which is enough corrosion that equipment would not likely last “for a long time”. Dilute sulfuric acid is very corrosive and 316L stainless steel is not recommended at all. On paper, a better choice for both carbonic acid and dilute sulfuric acid is Alloy 20, a nickel based alloy. If you are dealing with a mixture, it would be best to test potential alloy choices in the lab since mixtures can behave differently than their individual components. Impurities can also have an effect so use of representative samples for lab testing is important.