Q. Define corrosion-resistant nickel-based alloys?

The corrosion-resistant nickel-based alloys offer a significant improvement in corrosion resistance to sulphuric acid over the 300 series stainless steels.   A broader range of concentrations can be handled; however, temperature is still a limiting factor.

A number of corrosion resistant nickel alloys are commercially available.  The Iso-Corrosion Charts for several common alloys.  Each alloy typically has its own advantages.  In selecting a specific alloy for a given service, some in situ corrosion testing is recommended.

Alloy-20 (Carpenter 20Cb₃) and Incoloy 825 are two readily available commercial nickel-based alloys that have superior corrosion resistance to a broad range of H₂SO₄ concentrations.  Higher nickel-based alloys, such as Hastelloy B, Hastelloy C / C276 and Hastelloy G, also offer excellent resistance to H₂SO₄.