Material of dilute nitric acid storage tank
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According to the corrosion manual, both 304 stainless steel and aluminum can resist corrosion by dilute nitric acid. In practical applications, what material is suitable for use in tanks that store dilute nitric acid? Discussion is welcome.
Hydrogen nitrate storage tanks are made of 304 steel; the chromium content in 304 steel enables the formation of a stable oxide protective layer, which provides corrosion resistance. Such tanks are resistant to corrosion when the temperature is below 70 degrees Celsius and the nitric acid concentration is 65%, or when the temperature is below 100 degrees Celsius and the nitric acid concentration is below 60%. Aluminum does not suit use in hydrogen nitrate storage tanks as it dissolves in dilute nitric acid; however, aluminum can withstand corrosion from concentrated nitric acid well, thanks to the formation of a stable alumina protective layer on its surface, a phenomenon known as passivation.
Materials suitable for dilute nitric acid applications include: 1. Chromium and nickel stainless steels, such as 304, 304L, 321, 316, 316L, 302, and other materials produced by domestic manufacturers； 2. Carbon steel lined with PTFE ； 3. Pure titanium and stainless steel, but expensive. It is recommended to use chromium and nickel stainless steel. Aluminum is not resistant to corrosion by dilute nitric acid, but it is resistant to corrosion by concentrated nitric acid. Aluminum can resist corrosion by nitric acid solutions with a concentration of 3% or less, but it has poor strength, and its cost-performance ratio is far lower than that of chromium-nickel stainless steel.
Chromium stainless steel is the best and most cost-effective option
It is made of stainless steel, which facilitates manufacturing and material procurement.
Why not use plastic materials such as RPP/PVC?
Ferritic stainless steel materials should be used; typical grades include 00Cr12, 1Cr17, 00Cr17Mo, 00Cr30Mo2, etc. As the content of WCr increases, the acid resistance improves, and the addition of Mo further enhances both acid resistance and resistance to stress corrosion.
Reply to 7# suqianyangkang: Stainless steel containing Mo does not have better corrosion resistance to nitric acid than ordinary stainless steel; in some cases, its resistance is even lower! -\"Corrosion Data and Material Selection Manual\"