Hastelloy B2 is a nickel-molybdenum alloy that has obvious resistance to reducing environments such as hydrogen chloride gas, sulfuric acid, acetic acid, and phosphoric acid. Hastelloy B2 is resistant to pure sulfuric acid and some non-oxidizing acids. The alloy cannot be used where there are oxidizing pollutants in oxidizing media or reducing media. If iron or copper is used in a system containing hydrochloric acid, alloy B2 may fail prematurely.