Hastelloy C276 vs C22 for Acid Service

Choosing between Hastelloy C276 and Hastelloy C22 usually comes down to the acid mix, oxidising power and temperature of your process. Both are Ni-Cr-Mo alloys we stock in Mumbai as plate, sheet, bar and pipe, and both ship with the mill’s original EN 10204 3.1 certificate. This note is a practical comparison for fabricators and plant engineers in India — not a substitute for your corrosion engineer’s sign-off.

Quick identity

Hastelloy C276 (UNS N10276, W.Nr 2.4819) is the long-established Ni-Cr-Mo-W grade for severe reducing and mixed-acid service. Plate and sheet to ASTM B575, bar to ASTM B574, seamless pipe and tube to ASTM B622, welded to ASTM B619/B626. Full grade page: Hastelloy C276

Hastelloy C22 (UNS N06022, W.Nr 2.4602) has higher chromium than C276, with tungsten, for stronger resistance to oxidising acids and wet chlorine-bearing media. Same ASTM form family. Full grade page: Hastelloy C22

Chemistry that drives acid behaviour

Typical published ranges (wt%). C276: Ni balance; Cr 14.5–16.5; Mo 15.0–17.0; W 3.0–4.5; Fe 4.0–7.0; Co 2.5 max; Mn 1.0 max; V 0.35 max; C 0.01 max. C22: Ni balance; Cr 20.0–22.5; Mo 12.5–14.5; W 2.5–3.5; Fe 2.0–6.0; Co 2.5 max; Mn 0.50 max; V 0.35 max; C 0.015 max. Higher chromium in C22 helps in oxidising acids (nitric blends, wet Cl2, hypochlorite). Higher molybdenum and tungsten in C276 helps in reducing acids such as hot hydrochloric and in many wet H2S / chloride mixes.

When C276 is usually preferred

Hot hydrochloric acid and many reducing chloride environments.

Mixed acids where reducing conditions dominate.

Sour-gas and pollution-control equipment already specified to C276.

When the project MTC and welding procedure already lock C276 (UNS N10276).

When C22 is usually preferred

Oxidising acid streams, including nitric + chloride blends.

Wet chlorine, chlorine dioxide and hypochlorite service.

Cases where higher chromium is specified for oxidising upset conditions.

When the designer wants a C-family upgrade for oxidising resistance without leaving Ni-Cr-Mo.

Forms we supply (both grades)

Plate and sheet cut to size or into circles with the heat number kept on every piece; round bar; seamless and welded pipe and tube; flanges and fittings on request. Estimate weight with the metal weight calculator before you ask for a quote. See also Hastelloy sheet and plate and Hastelloy pipe and tube.

Traceability

Every supply carries the mill’s original EN 10204 3.1 test certificate. Heat numbers are marked on cut pieces and can be PMI-checked before dispatch. Ganesh Metals has been a high-nickel alloy stockist and supplier in Mumbai since 1992, with pan-India supply including SEZ units. ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018.

FAQ

Q: Is C22 always better than C276?

A: No. C22 is stronger in many oxidising acids; C276 remains the usual choice for several reducing and mixed-acid duties. Send temperature, concentration and media and we will help you compare stocked forms.

Q: Do you stock both C276 and C22 plate in Mumbai?

A: Yes. We supply both grades as plate, sheet, bar and pipe from Mumbai stock, cut to size with EN 10204 3.1 MTC.

Q: Which ASTM specs apply?

A: Plate/sheet ASTM B575, bar ASTM B574, seamless pipe/tube ASTM B622, welded pipe ASTM B619, welded tube ASTM B626, for both C276 and C22 as ordered.

Share your media, temperature and size list and we will confirm Mumbai stock and the MTC heat number. Contact