Inconel vs Hastelloy – Choosing the Right Nickel Alloy Pipe for Harsh Environments
Nickel-based superalloys are the workhorses of the most demanding industrial environments — applications where temperature extremes, highly corrosive media, and mechanical stress would rapidly degrade conventional stainless steel grades. Among these, Inconel and Hastelloy are the two most widely specified families. Understanding the differences between them is essential for engineers, project managers, and procurement teams working in oil and gas, chemical processing, aerospace, and power generation.
Metinox Overseas supplies a comprehensive range of nickel alloy pipes, tubes, and flanges across both families. Explore our Hastelloy Pipes, Inconel 625 Pipes, and Inconel 600 Pipes. For flanges, browse our Hastelloy C276 Flanges and Inconel 625 Flanges.
What Is Inconel?
Inconel is a family of nickel-chromium superalloys manufactured by Special Metals Corporation, though the generic grades are widely produced by multiple manufacturers. Key characteristics include:
- High nickel-chromium base composition provides a thick, stable oxide layer that protects against oxidation at extreme temperatures
- Exceptional high-temperature strength — Inconel retains structural integrity above 1000°C, making it indispensable for jet engine components, exhaust systems, and furnace hardware
- Good resistance to oxidising and mildly reducing environments
The most common grades in industrial piping are:
- Inconel 600 (UNS N06600): General-purpose high-temperature alloy resistant to oxidation and chloride stress corrosion cracking
- Inconel 601 (UNS N06601): Enhanced aluminium addition for superior oxidation resistance at very high temperatures
- Inconel 625 (UNS N06625): Adds niobium for exceptional fatigue and thermal-fatigue strength; widely used in subsea and marine
What Is Hastelloy?
Hastelloy alloys — originally developed by Haynes International — are primarily nickel-molybdenum-chromium alloys engineered for maximum corrosion resistance in chemical and process environments. Their distinguishing features include:
- Exceptional resistance to both oxidising and reducing chemical environments
- Outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking in aggressive media
- Resistance to wet chlorine gas, chlorine dioxide, and hypochlorite — environments that would destroy most other alloys
Key grades include:
- Hastelloy C276 (UNS N10276): The benchmark nickel alloy for chemical process piping, resisting a broad range of acids, solvents, and oxidisers
- Hastelloy C22 (UNS N06022): Higher chromium than C276 for improved resistance to oxidising media
- Hastelloy B2 (UNS N10665): Highest molybdenum content for superior resistance to hydrochloric acid
Head-to-Head: Inconel vs Hastelloy
Temperature Performance
Inconel grades excel at very high temperatures. Inconel 601 and 600 are specified for furnace components, heat treatment equipment, and gas turbine parts operating above 900°C. Hastelloy alloys are more temperature-capable than standard stainless steels but are primarily optimised for corrosion resistance at lower-to-moderate service temperatures.
Chemical Corrosion Resistance
Hastelloy dominates in chemical process environments. Hastelloy C276 resists virtually every known industrial chemical, including hydrochloric acid, sulphuric acid, and hypochlorite. Inconel grades offer good corrosion resistance in general environments and seawater but are specifically selected for their high-temperature mechanical properties rather than broad-spectrum chemical resistance.
Typical Application Environments
Choose Inconel when: high operating temperatures are the primary design driver, the application involves gas turbines, aerospace components, or high-temperature heat exchangers, or when combined high-temperature strength and seawater resistance is needed (Inconel 625).
Choose Hastelloy when: the application involves aggressive chemical environments, strong acids, chlorinated solvents, or highly corrosive process streams at moderate temperatures in chemical plants, pollution control systems, or pharmaceutical manufacturing.
| Factor | Inconel (600 / 625) | Hastelloy (C276 / C22) |
|---|---|---|
| Primary strength | High-temperature performance | Broad chemical corrosion resistance |
| Max service temp | Up to 1100°C+ | Moderate-to-high (process temps) |
| Acid resistance | Good (general) | Excellent (HCl, H₂SO₄, hypochlorite) |
| Seawater / chloride | Very good (esp. 625) | Excellent |
| Typical industries | Aerospace, oil & gas, power | Chemical, pharma, pollution control |
Metinox Overseas Nickel Alloy Product Range
- Inconel 600 Pipes & Tubes
- Inconel 601 Pipes & Tubes
- Inconel 625 Pipes & Tubes
- Incoloy 800/800H Pipes
- Incoloy 825 Pipes
- Hastelloy Pipes & Tubes
- Monel 400 Pipes & Tubes
- Nickel Alloy Flanges
Frequently Asked Questions
Yes. Both families are weldable using GTAW (TIG) and GMAW processes. Welding dissimilar nickel alloys requires careful selection of filler metal — consult your welding engineer and request ASME Section IX compliance from your pipe manufacturer.
Both are nickel-chromium-molybdenum alloys. C22 has a higher chromium content (22% vs 16%), giving it better resistance to oxidising acids and localised corrosion. C276 has higher molybdenum (16% vs 13%), providing superior resistance to reducing acids and pitting in chloride environments. C276 is the more widely used general-purpose grade.
Yes. All nickel alloy products from Metinox Overseas are supplied with full mill test reports and can be third-party inspected by TUV, SGS, or Bureau Veritas as per project requirements. Contact us to discuss your inspection requirements.
Source Inconel, Hastelloy, Monel, and Incoloy pipes and flanges from Metinox Overseas. Visit our Special Alloys Pipes & Tubes page or contact us for a tailored quotation.
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