Hastelloy vs Inconel: Nickel-Alloy Selection Guide for Instrumentation Fittings, Valves & Tubing
Hastelloy and Inconel are both nickel-based alloy families built to resist corrosion, though they take different paths to get there. Hastelloy relies on nickel-molybdenum and nickel-chromium-molybdenum chemistry, which suits it to aggressive acids. Inconel leans on nickel-chromium and nickel-chromium-molybdenum chemistry instead, built for high-temperature and oxidizing conditions. This guide compares the two as materials for fluid-system instrumentation: compression fittings, valves, manifolds and tubing. It has nothing to do with aerospace forgings, weld filler wire, or mill plate. Crestflo supplies both families, but only in instrumentation product forms.
Hastelloy® is a registered trademark of Haynes International, Inc. Inconel®, Incoloy® and Monel®, meanwhile, belong to Special Metals Corporation. Crestflo has no affiliation with either company, and neither endorses nor sponsors it. These alloy names appear here only to identify the standardized, UNS-designated materials that Crestflo machines into finished parts.
Quick Answer: Hastelloy vs Inconel: Which Nickel Alloy to Choose
Pick Hastelloy when you're up against aggressive reducing or mixed acids, plus localized corrosion. Hastelloy C-276 and C-22 are the top choices there, and the B-grades handle hot hydrochloric acid better than anything else in the family. Pick Inconel instead when the threat is high-temperature oxidation, or when you need serious mechanical strength: Inconel 601 and 600 hold up well against oxidation, Inconel 625 works as a solid all-around Ni-Cr-Mo option, and precipitation-hardened Inconel 718 delivers the highest strength in the group. A lot of these applications overlap, though, so the exact grade you choose usually counts for more than which family it belongs to.
| Service priority | Choose Hastelloy (grade) | Choose Inconel (grade) |
|---|---|---|
| Reducing / mixed acids (HCl, H₂SO₄) | C-276, C-22, B-3 | 625 (moderate) |
| Localized corrosion (pitting / crevice) | C-276, C-22 | 625 |
| High-temperature oxidation | X | 601, 600 |
| Maximum mechanical strength / hardness | C-276 (solid-solution) | 718 (precipitation-hardened) |
| Sour service (NACE MR0175 / ISO 15156) | C-276, C-22 | 625, 825 |
| General "safe default" corrosion-resistant alloy | C-276 | 625 |
Values here reflect the standard published behavior of these UNS-designated alloys, and they can be customized to your service. Confirm the specific grade and condition against your media, your temperature and the applicable code.
What Are Hastelloy and Inconel? Nickel-Alloy Families Explained
It comes down to one element. Hastelloy leans on molybdenum; Inconel leans on chromium. That single difference in chemistry drives nearly every selection decision that follows.
Hastelloy is Haynes International's trade name for a family of nickel-molybdenum (Ni-Mo) and nickel-chromium-molybdenum (Ni-Cr-Mo) corrosion-resistant alloys. A high molybdenum content drives that resistance to reducing acids, pitting and crevice attack; in the C-grades, tungsten adds to the effect. Five grades anchor the family: C-276, C-22, B-2, B-3 and X.
Inconel is the trade name Special Metals uses for its family of nickel-chromium (Ni-Cr) and nickel-chromium-molybdenum (Ni-Cr-Mo) alloys. Chromium content is high, and that's what gives these alloys resistance to oxidizing environments and to oxidation at high temperatures. Niobium and molybdenum, added in grades 625 and 718, boost both corrosion resistance and mechanical performance. Five grades form the core lineup: 600, 601, 625, 718 and 825. The last one, Incoloy 825, is an iron-nickel-chromium alloy from the same Special Metals stable, and it's often specified right alongside Inconel.
Both rank above 316 stainless in the corrosion-resistant-alloy hierarchy, sitting below the specialized copper-nickel branch. The copper-based Monel alloys, which handle hydrofluoric acid and seawater rather than strong acids, get their own writeup: see the Inconel vs Monel comparison for the details. Crestflo's instrumentation materials hub covers the full material range.
Hastelloy and Inconel: Other Names, UNS Numbers & Werkstoff Designations
Engineers specify these alloys under several equivalent identifiers, and any one of them might show up on a drawing or purchase order. Hastelloy C-276 is UNS N10276, also known as Werkstoff 2.4819. C-22 goes by N06022 (2.4602), B-2 by N10665 (2.4617), and B-3 by N10675 (2.4600). Hastelloy X rounds out that group as N06002 (2.4665). Switch to the Inconel side and 600 becomes N06600 (2.4816); 601 is N06601 (2.4851); 625 is N06625 (2.4856); 718 is N07718 (2.4668). Incoloy 825 falls under N08825 (2.4858). People call these alloys high-nickel alloys, nickel-based superalloys, or corrosion-resistant alloys (CRA) depending on who's writing. The query shows up phrased both ways, "Hastelloy vs Inconel" and "Inconel vs Hastelloy," and neither version changes the meaning.
Hastelloy vs Inconel Composition: Nominal Chemistry Compared
The nominal chemistries below explain the performance split. Molybdenum and tungsten concentrate in the Hastelloy grades, chromium in the Inconel grades, and niobium and aluminum drive the precipitation-hardening and high-temperature behavior of 718 and 601. Put simply, Hastelloy properties come from molybdenum-driven resistance to reducing acids. Inconel properties, on the other hand, come from chromium-driven oxidation resistance and high-temperature strength. Chemistry is the reason each family behaves the way it does. Each alloy name links to its full instrumentation material page.
| Alloy | UNS | Werkstoff | Ni | Cr | Mo | Fe | Other (nominal) |
|---|---|---|---|---|---|---|---|
| Hastelloy C-276 | N10276 | 2.4819 | Bal | 15–16 | 15–17 | 4–7 | W 3–4.5 |
| Hastelloy C-22 | N06022 | 2.4602 | Bal | 20–22.5 | 12.5–14.5 | 2–6 | W 2.5–3.5 |
| Hastelloy B-2 | N10665 | 2.4617 | Bal | ≤1 | 26–30 | ≤2 | Co ≤1 |
| Hastelloy B-3 | N10675 | 2.4600 | Bal | ~1.5 | 27.5–29.5 | ~1.5 | — |
| Hastelloy X | N06002 | 2.4665 | Bal | 20.5–23 | 8–10 | 17–20 | Co 0.5–2.5, W 0.2–1 |
| Inconel 600 | N06600 | 2.4816 | ≥72 | 14–17 | — | 6–10 | Cu ≤0.5 |
| Inconel 601 | N06601 | 2.4851 | 58–63 | 21–25 | — | Bal | Al 1–1.7 |
| Inconel 625 | N06625 | 2.4856 | ≥58 | 20–23 | 8–10 | ≤5 | Nb 3.15–4.15 |
| Inconel 718 | N07718 | 2.4668 | 50–55 | 17–21 | 2.8–3.3 | Bal | Nb 4.75–5.5, Ti 0.65–1.15 |
| Incoloy 825 | N08825 | 2.4858 | 38–46 | 19.5–23.5 | 2.5–3.5 | Bal | Cu 1.5–3, Ti 0.6–1.2 |
These figures represent nominal ranges under the relevant ASTM/UNS designations, given in weight percent. The actual heat chemistry appears on the EN 10204 material test certificate. Density runs about 8.89 g/cm³ for Hastelloy C-276, and Inconel 625 comes in lower, at roughly 8.44 g/cm³.
Hastelloy vs Inconel Corrosion Resistance: Which Resists What
Chemistry draws the line here. Molybdenum and tungsten give the Hastelloy C- and B-grades their edge in reducing acids: hydrochloric, sulfuric, mixed or contaminated acid streams. They also hold up best against localized pitting and crevice corrosion. Chromium is what makes the Inconel grades the stronger pick in oxidizing environments, especially where oxidation resistance at temperature matters. Some services throw both oxidizing and reducing conditions at a material at once. That's where Hastelloy C-276, C-22, and Inconel 625 earn their keep: versatile Ni-Cr-Mo grades built to bridge the gap.
| Environment | Hastelloy grade fit | Inconel grade fit |
|---|---|---|
| Hydrochloric acid (HCl) | B-3, C-276 (strong) | Limited |
| Sulfuric acid (H₂SO₄) | C-276, C-22 | 625, 825 (moderate) |
| Wet chlorine / mixed acids | C-276 (excellent) | 625 (moderate) |
| Seawater / chloride pitting & crevice | C-276, C-22 | 625 |
| Sour service / H₂S (NACE) | C-276, C-22 | 625, 825 |
| Oxidizing acids (e.g. nitric) | C-22 | 625, 601, 600 |
For a full media-by-alloy view, see the corrosion-by-media alloy matrix and the PREN comparison table. Sour service calls for different choices. Hastelloy C-276/C-22 and Inconel 625/825 are the corrosion-resistant alloys most commonly specified here, and both are qualified to NACE MR0175 / ISO 15156. Before locking in a grade, though, confirm the exact metallurgical condition using the NACE MR0175 standard page and the sour-service selection workflow.
Hastelloy vs Inconel at High Temperature: Oxidation & Heat Resistance
For sustained high-temperature oxidizing service, the chromium- and aluminum-bearing grades come out on top. Inconel 601 gives the best oxidation resistance of the group, with Inconel 600 not far behind. Hastelloy X, meanwhile, is the gas-turbine-class Hastelloy, built for high-temperature strength and oxidation resistance together. Inconel 625 holds its strength and oxidation resistance well across a wide range of conditions. The Hastelloy C- and B-grades get chosen for wet corrosion rather than extreme dry heat, so their continuous-service temperature niche sits lower and more moderate. Oxidation resistance and strength-at-temperature aren't the same thing, though people often treat them that way. One measures surface stability in hot gas; the other measures load-bearing capacity. A grade can win on one and fall short on the other.
Hastelloy vs Inconel Mechanical Properties: Strength & Hardness: Is Hastelloy Stronger Than Inconel?
Among these alloys, Inconel's mechanical properties peak with precipitation-hardened Inconel 718, which delivers the highest strength and hardness; it's age-hardened through niobium, titanium and aluminum additions, and that's why it dominates high-load applications. Hastelloy C-276 takes a different route: solid-solution strengthened, tough and ductile with good strength, but nowhere near as hard as aged 718. The question "is Hastelloy stronger than Inconel?" really comes down to the grade in play. 718 outperforms the standard corrosion grades on strength, while engineers reach for a solid-solution Hastelloy or Inconel when corrosion resistance matters most. As for what metal is harder than Inconel, tougher materials do exist outside these alloy families: cobalt-based superalloys, tungsten carbide, ceramics. Within nickel alloys, though, aged 718 sits near the top.
Hastelloy vs Inconel Weldability, Machinability & Fabrication
Both families take to welding well when paired with matching or compatible nickel-alloy filler metals; Hastelloy C-276 and C-22 in particular weld very well. Inconel 718 is precipitation-hardened, so it doesn't come back to full strength across a weld until it's gone through a post-weld solution-and-age heat treatment. All of these alloys work-harden as you cut them. Tooling, feeds and speeds get set with that in mind. Crestflo machines both families in-house on CNC, VMC and EDM equipment and handles orbital-weld fittings as well. The alloy you're comparing on paper, in the end, is the alloy your finished part is actually cut from.
Hastelloy vs Inconel Grade Head-to-Heads: C-276 vs 625, C-22 vs 625, 718 vs C-276
Below, the head-to-head pairings tackle the grade-level decisions that matter most. Treat each one as a starting point, not a final answer, and check it against your media, temperature and code.
| Match-up | Key difference | Pick this when |
|---|---|---|
| Hastelloy C-276 vs Inconel 625 | C-276 has more Mo+W for reducing/mixed acids; 625 adds Nb and higher-temperature versatility | Reducing/mixed acids → C-276; oxidizing/high-temp or higher strength → 625 |
| Hastelloy C-22 vs Inconel 625 | C-22 balances oxidizing and reducing resistance; 625 leans oxidizing/high-temp | Broad mixed-acid + oxidizing → C-22; general Ni-Cr-Mo service → 625 |
| Inconel 718 vs Hastelloy C-276 | 718 is precipitation-hardened for strength; C-276 is corrosion-first | High mechanical load → 718; aggressive acids → C-276 |
| Hastelloy B-3 vs Inconel | B-3 is a Ni-Mo grade for hot HCl with little chromium | Hot hydrochloric acid → B-3; oxidizing exposure → an Inconel grade |
| Hastelloy X vs Inconel 601 / 625 | X and 601 are high-temperature oxidation grades | Gas-turbine-class heat → X or 601 |
| Hastelloy vs Incoloy 825 | 825 adds copper for sulfuric acid and stress-corrosion resistance | Sulfuric/phosphoric acid & SCC → 825; strong reducing acids → a Hastelloy C-grade |
See Inconel 625 vs 825 for a closer look at that Inconel comparison. For the stainless baseline decision, Alloy 20 vs 316 covers the details.
Which Alloy for Instrumentation Fittings, Valves & Tubing
Crestflo supplies both families as finished instrumentation components, not mill forms. Compression and double-ferrule tube fittings come in high-nickel alloys up to 2" (50 mm) OD, in single- and double-ferrule designs. Instrumentation valves run from 1/16" to 1". There are 2/3/5-way manifolds too, plus seamless or welded instrumentation tubing. All of it ships in imperial and metric sizing alike.
| Product form | Size range | Options | Alloys |
|---|---|---|---|
| Compression / double-ferrule fittings | Up to 2" (50 mm) OD | Single & double ferrule; hardened or non-hardened | C-276, C-22, B-2, B-3, X; Inconel 600/601/625/718/825 |
| Instrumentation valves | 1/16" to 1" | Threaded or tube-fitting ends; handle & seal options | Same nickel-alloy range |
| Manifolds (2/3/5-way) | 1/16" to 1" | Direct-mount & remote; 100% seat & shell leak tested | Same nickel-alloy range |
| Instrumentation tubing | Per applicable OD/wall tables | Seamless & welded; annealed | Same nickel-alloy range |
Compression tube fittings carry a performance qualification to ASTM F1387. Instrumentation valves, meanwhile, conform to the applicable valve standards, among them ASME B16.34, along with the relevant API testing standards (API 598/602). Take a look at Crestflo's nickel-alloy instrumentation valves, the needle valve, the 3-valve manifold, and the alloy instrumentation tubing.
Grade-specific forms exist too: Hastelloy C-276 tube fittings and Inconel 625 tube fittings are both available.
Hastelloy vs Inconel Cost & Lead Time
Both are premium nickel alloys, and pricing for each comes down to alloy content. Hastelloy grades lean on high molybdenum and tungsten; Inconel grades lean on high nickel-chromium plus niobium. Inconel 718 costs more than the rest, though, because of its precipitation-hardening processing. The relative cost between two grades follows their alloy loading, not some fixed ratio. Current pricing hinges on mill quotation, so exact figures come per inquiry. Crestflo competes on lead time and landed cost: standard items sit in ready stock, specials get made to order, and delivery typically runs 6–8 weeks against the 20-plus weeks common from the majors. Pricing stays competitive even after US duties are factored in. Check the lead-time capability, the tariff cost advantage, and the alloy lead-time & cost benchmark for the details.
How to Choose Between Hastelloy and Inconel: A 5-Step Workflow
- Identify the corrosion driver. Reducing or mixed acids, especially with localized attack, point toward Hastelloy C-276 / C-22 (or B-3 for hot HCl). Oxidizing or high-temperature service calls for an Inconel grade instead.
- Set the temperature. Sustained high-temperature oxidation favors Inconel 601 / 600 or Hastelloy X, while moderate wet-corrosion service favors the Hastelloy C-grades.
- Define the mechanical load. High strength or hardness requirements point to precipitation-hardened Inconel 718. If corrosion resistance is the priority, solid-solution grades handle it.
- Apply the code requirement. For sour service, check the grade against NACE MR0175 / ISO 15156, then apply whatever valve or fitting standard applies.
- Weigh cost and lead time. Both options run at a premium, so pick the leanest grade that still meets the service and plan for a 6–8 week lead time to source it.
The material-selection-by-service guide walks this workflow across the full alloy range.
Standards, Certification & Traceability
Crestflo holds ISO 9001 / 14001 / 45001 and PED certification. Every part carries a heat or lot number, so full traceability is never in question. EN 10204 MTC 3.1 comes as standard, with 3.2 available on request, and PMI verification is part of the package. Each product type follows its own standard: compression fittings meet ASTM F1387, valves are built to ASME B16.34 and the relevant API testing standards, and materials conform to specifications such as ASTM A269, A276 and A479. Where sour-service qualification is needed, corrosion-resistant grades are supplied to NACE MR0175 / ISO 15156. NDT is done in-house and backed up by destructive testing at ISO/IEC 17025-accredited laboratories, with third-party inspection available on request. Datasheets and CAD models aren't posted as public downloads, but customers can request them directly.
Material comes from India, though we can pull US or European melt if you need it, and every batch stays fully traceable from start to finish. For TAA/DFARS handling, Crestflo's US origin and compliance page has the details.
Why Crestflo for Hastelloy & Inconel Instrumentation
Crestflo is the instrumentation division of an export house that's four decades old, recognized by the Government of India, with a proven delivery record across the Middle East and now serving the US market too. Both alloy families are machined in-house, from bar and tube through to finished fittings, valves, manifolds and tubing. That's a maker's capability, not a reseller's catalog. It means the exact grade compared here can be delivered as a certified, traceable instrumentation part, with small minimum order quantities and private-label programs on offer. We Engineer Confidence.
Ready to move forward? Request a quote and include your grade, form and service conditions, or simply request a sample. Need a grade cross-reference against your current part? Ask our engineering team for one through the RFQ. Crestflo handles US inquiries at sales@crestflousa.com, +1 346 594 9005, Houston, TX.
Frequently Asked Questions: Hastelloy vs Inconel
Is Hastelloy better than Inconel?
Neither one wins across the board; it really comes down to the service. Hastelloy, especially C-276 and C-22, pulls ahead in reducing and mixed acids, and it handles localized pitting and crevice corrosion better than most alternatives. Inconel, on the other hand, takes the lead in high-temperature oxidation and, with 718, in mechanical strength. Pick the grade based on your media, temperature and load. That matters far more than which family the alloy belongs to.
What is another name for Hastelloy?
"Hastelloy" is a registered trademark of Haynes International. That's worth knowing up front. The alloys themselves fall into two general families: nickel-molybdenum and nickel-chromium-molybdenum, both known for resisting corrosion. Each grade also carries a UNS number. Hastelloy C-276, for instance, is UNS N10276, listed as Werkstoff 2.4819 under the German standard. C-22 goes by N06022, or 2.4602.
What metal is harder than Inconel?
Inconel 718, once precipitation-hardened, comes out the hardest of this group. Go outside the alloy family, though, and you'll find tougher customers still: cobalt-based superalloys, tungsten-carbide materials, ceramics. Hastelloy C-276, by contrast, relies on solid-solution strengthening. It's tough, it bends before it breaks, but it doesn't match aged 718 for hardness.
What is Hastelloy resistant to?
Hastelloy C-grades hold up against hydrochloric acid, sulfuric acid, wet chlorine, and mixed or contaminated acids. Pitting and crevice corrosion don't get much traction against them. The B-grades take a different tack: hot hydrochloric acid is where they really shine. Chromium adds another layer of protection too, giving the Hastelloy C family real strength in some oxidizing conditions. C-22 benefits from this most of all.
Hastelloy C-276 vs Inconel 625, which do I pick?
C-276 is the right choice for aggressive reducing or mixed acids, and for localized corrosion. Oxidizing or high-temperature service, especially where higher strength matters, calls for 625. Both are established corrosion-resistant alloys for sour service, and Crestflo machines each one into fittings and valves. Compare the Hastelloy C-276 material page and the Inconel 625 material page.
Which is more expensive, Hastelloy or Inconel?
Both alloys sit at the premium end of the nickel market, and cost tracks what's actually in them. Hastelloy leans on high molybdenum and tungsten content. Inconel 718 leans on nickel-chromium plus niobium, with heat-treat processing adding to the bill. Pricing moves with the mill quotation, so Crestflo provides exact figures per inquiry. Even after US duties, Crestflo holds a competitive edge, and lead time runs 6–8 weeks.
Are Hastelloy and Inconel suitable for sour (H₂S) service?
Yes. Hastelloy C-276, Hastelloy C-22, Inconel 625, and 825 are all widely used corrosion-resistant alloys, and each one is qualified to NACE MR0175 / ISO 15156. That said, the specific grade and metallurgical condition still need confirming against your actual partial pressure and temperature. Don't skip that step. See the NACE MR0175 page for the full breakdown.
Does Crestflo supply both Hastelloy and Inconel instrumentation parts?
Compression and double-ferrule fittings up to 2" (50 mm) OD, yes, we cover those. Instrumentation valves from 1/16" to 1" too, plus 2/3/5-way manifolds and tubing. All available in C-276/C-22/B-2/B-3/X and Inconel 600/601/625/718/825. Fittings carry performance qualification to ASTM F1387. Heat-number traceability comes standard, and so does EN 10204 MTC 3.1; 3.2 is available on request.
Where does Monel fit against Hastelloy and Inconel?
Monel is a nickel-copper alloy built for hydrofluoric acid and seawater, not the strongly oxidizing or strongly reducing acids other alloys handle. It fills a different corrosion niche entirely. For that comparison, see Inconel vs Monel.
Can I get small quantities or private label?
Yes, small minimum order quantities and private-label programs are open across both alloy families, along with made-to-print custom work. Start with a quote request and Crestflo will take it from there.
Related Comparisons & Material Pages
Continue with Inconel 625 vs 825, Inconel vs Monel, and Alloy 20 vs 316 for more detail. Want to dig into a single grade? The materials hub covers each one on its own page. Or browse the full set of guides in Crestflo's instrumentation fittings resource library.