When a corrosive environment exceeds the capability of 316L stainless steel or duplex grades, Hastelloy C-276 is typically the first nickel alloy the specification moves to. Its combination of high molybdenum and tungsten content delivers corrosion resistance across reducing acids, oxidising chloride environments, wet chlorine gas, and mixed acid service where stainless steel grades fail rapidly.

This guide covers the composition, properties, ASTM standards, corrosion resistance, key applications, and procurement specification for Hastelloy C-276. For nickel alloy selection context, see our Inconel 625 guide.

Composition and Designation

Hastelloy C-276 is a nickel-molybdenum-chromium alloy with the following nominal composition per ASTM B575 / UNS N10276:

• Ni: balance (~57%) · Mo: 15–17% (reducing acid resistance) · Cr: 14.5–16.5% (oxidising resistance) · W: 3–4.5% (pitting resistance) · Fe: 4–7% · C: 0.01% max

The high Mo and W combination is what distinguishes C-276. Molybdenum provides reducing acid resistance; tungsten extends pitting and crevice corrosion resistance in chloride environments. The ultra-low carbon content eliminates sensitisation risk in the welded condition — no post-weld heat treatment required.

Key Properties UNS N10276 at a Glance

Corrosion Resistance Where C-276 Outperforms

The defining characteristic of Hastelloy C-276 is its resistance across both oxidising and reducing corrosive environments — a capability very few alloys share:

• Hydrochloric acid (HCl): excellent resistance across all concentrations at moderate temperatures. No other commercially available alloy at this price point matches C-276 in HCl service.
• Sulphuric acid (H₂SO₄): outstanding resistance across a wide concentration and temperature range, including hot concentrated H₂SO₄ conditions that destroy stainless steel rapidly.
• Wet chlorine and chlorinated solvents: the high Mo and W content provides resistance to wet chlorine gas, hypochlorite solutions, and chlorinated organic solvents — environments that cause rapid pitting of stainless steel.
• Sour gas service (H₂S + CO₂ + chlorides): accepted under NACE MR0175 / ISO 15156 Part 3 as a CRA — see our NACE MR0175 guide for compliance details
• Reducing and mixed acids: phosphoric acid, formic acid, acetic acid, and mixed acid environments where stainless steel grades suffer accelerated corrosion.
• C-276 is not recommended for fuming nitric acid or hot concentrated H₂SO₄ above 70% without reducing agents — higher chromium grades should be evaluated for these environments. For sour service compliance, see our NACE MR0175 / ISO 15156 guide.

ASTM Standards for Hastelloy C-276 Supply

Specify the standard and UNS number together on every purchase order. C-276 is supplied to:

• ASTM B622 / SB-622: seamless pipe and tube  ·  B619 / SB-619: welded pipe  ·  B626 / SB-626: welded tube
• ASTM B575 / SB-575: plate, sheet, and strip  ·  B564 / SB-564: forgings  ·  B574 / SB-574: bar

All supply should be accompanied by an EN 10204 3.1 MTC as a minimum — confirming chemical composition, mechanical properties, and heat number traceability for the specific material supplied. For offshore and classification society projects, EN 10204 3.2 is required. See our EN 10204 2.2 vs 3.1 vs 3.2 certification guide for full details.

Key Applications

Chemical Processing

The dominant alloy for reactors, heat exchangers, piping, and vessels handling HCl, H₂SO₄, acetic acid, chlorinated organics, and mixed acid process streams. Resistance across both oxidising and reducing environments eliminates the need for different alloys in mixed chemistry service.

Oil and Gas and Sour Service

Subsea and downhole components in sour gas wells (H₂S + CO₂ + chlorides), chemical injection systems, and wellhead hardware where combined corrosion exceeds 316L or duplex capability. Accepted under NACE MR0175 / ISO 15156 Part 3 as a CRA.

Flue Gas Desulphurisation (FGD)

Power plant FGD systems handling wet SO₂ and chloride-containing scrubber liquors are one of the largest application areas for C-276 — the combined SO₂, HCl, and chloride environment at elevated temperatures is where C-276 consistently outperforms all alternatives.

How to Specify Hastelloy C-276 on a Purchase Order

A correctly specified Hastelloy C-276 purchase order must include:

• Grade and UNS: 'Hastelloy C-276, UNS N10276' — never 'C276' or 'C-276' alone, which are not standardised designations internationally
• ASTM standard and product form: e.g. 'ASTM B622 UNS N10276 seamless pipe' — specify the product-form standard explicitly
• Condition: 'solution annealed and quenched' — state explicitly
• Dimensions: OD and wall (pipe/tube) · thickness and width (plate) · diameter and length (bar) — to ASTM tolerances
• Certificate type: EN 10204 3.1 MTC minimum — EN 10204 3.2 for offshore and classification-governed projects

For guidance on the most common specification errors when ordering engineered alloys, see our material specification mistakes guide.

Source Certified Hastelloy C-276 from Dubai

Nifty Alloys LLC supplies certified Hastelloy C-276 (UNS N10276 / DIN 2.4819) in pipe, tube, plate, sheet, bar, and forgings — ASTM B622, B575, B564, B574, B626, and B619 — with EN 10204 3.1 MTCs, to oil and gas, chemical processing, offshore, and industrial projects globally. View our full nickel alloys range or visit our quality standards page for certification capabilities.