Hastelloy C22 (UNS N06022 / 2.4602) and Hastelloy C276 (UNS N10276 / 2.4819) supplier
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While both belong to the "C" family of nickel alloys and exhibit outstanding corrosion resistance, their distinct chemical profiles alter their performance under specific technical conditions. Below is a comprehensive engineering and procurement comparison between Alloy C22 and Alloy C276.
Chemical composition:
Alloy C22 pipe (UNS N06022) has a slightly lower chromium content than Hastelloy alloy C276 (UNS N10276). C22 contains 20-22% chromium, while C276 contains 14.5-16.5% chromium. C22 also has a higher molybdenum content (12.5-14.5%) compared to C276 (15-17%).
| Element | Alloy C22 (UNS N06022) | Alloy C276 (UNS N10276) |
| Nickel (Ni) | Balance | Balance |
| Chromium (Cr) | 20.0 – 22.5 | 14.5 – 16.5 |
| Molybdenum (Mo) | 12.5 – 14.5 | 15.0 – 17.0 |
| Tungsten (W) | 2.5 – 3.5 | 3.0 – 4.5 |
| Iron (Fe) | 2.0 – 6.0 | 4.0 – 7.0 |
| Carbon (C) | ≤ 0.015 | ≤ 0.010 |
Common Production Standards
Both alloys are manufactured under strict international regulatory frameworks depending on the product format:
Pipes & Tubes: ASTM B622 (Seamless), ASTM B619 / ASME SB619 (Welded)
Fittings & Flanges: ASTM B366, ASTM B564 / ASME SB564
Bars & Rods: ASTM B574 / ASME SB574
Plates & Sheets: ASTM B575 / ASME SB575
Corrosion Resistance: Oxidizing vs. Reducing Environments
The differing levels of chromium and molybdenum dictate how each metal handles severe corrosion profiles.
Oxidizing and Aggressive Aqueous Media (Alloy C22 Advantage)
Because Alloy C22 contains significantly higher chromium levels, it demonstrates vastly superior protection against oxidizing environments. It offers premium resistance to wet chlorine, nitric acid mixtures, and severely contaminated oxidizing acid streams containing ferric or cupric ions. Furthermore, its overall Pitting Resistance Equivalent Number (PREN) gives it an edge against severe localized pitting and crevice corrosion in chloride-heavy process streams.
Severe Reducing Media (Alloy C276 Advantage)
Alloy C276 excels in strongly reducing environments thanks to its elevated molybdenum content. It is a premier industry choice for handling highly aggressive reducing agents like hot hydrochloric acid, sulfuric acid, and phosphoric acid. It also remains exceptionally reliable against sulfide stress cracking and sour gas environments common in oil exploration.
Weldability and Thermal Stability
When fabricating heavy-walled process equipment, industrial boilers, or pre-fabricated pipe spools, thermal stability is critical.
Alloy C22 is engineered with optimized carbide stability. It resists the formation of grain-boundary precipitates within the weld heat-affected zone (HAZ) far better than many older formulations. This property makes it highly adaptable for as-welded chemical vessel assemblies without immediate post-weld annealing.
Alloy C276 possesses an ultra-low carbon and silicon content to inhibit weld-zone carbide precipitation. However, due to its chemistry, careful control over the heat input during welding is required to minimize any minor susceptibility to hot cracking or intergranular corrosion in highly severe service environments.
Typical Applications & Industry Uses
Alloy C22 Applications:
Pharmaceutical production plants (demanding clean-in-place configurations)
Flue gas desulfurization (FGD) scrubbers
Cellulose and paper pulp bleach plants
Nuclear fuel reprocessing and aggressive wastewater reclamation
Alloy C276 Applications:
Downhole equipment for sour gas (H2S) oilfields
Chemical process reactors handling high concentrations of hot chlorides
Marine exhaust gas scrubbing systems
Petrochemical refineries and organic acid production
Summary: Which Alloy Fits Your Project?
Choose Hastelloy C22 if your industrial system encounters mixed, highly fluctuating chemical streams that involve strong oxidizing acids, or if the design demands extensive welding fabrication without post-weld heat treatment.
Choose Hastelloy C276 if your system operates primarily under severe reducing acid exposures (such as hydrochloric or sulfuric acid loops) or is exposed to deep downhole oil and gas environments.
Partner with an Experienced Metallurgical Supplier
As a leading global manufacturer and exporter, Zhengzhou Huitong Pipeline Equipment Co., Ltd. (HT PIPE) supplies a complete ecosystem of high-performance nickel alloy products. We offer fully certified seamless and welded pipes, forged flanges, butt-weld pipe fittings, plates, and customized pre-fabricated pipe spools in both Hastelloy C22 and Hastelloy C276, complete with comprehensive Material Test Reports (MTRs).
Need a technical consultation or a competitive project quotation?
Contact our engineering team directly at market@htpipe.com or send a WhatsApp inquiry to +86 193 3990 0201. Let us help ensure your systems are engineered for absolute safety and long-term performance.
