Hastelloy C-276 Tube Fittings (UNS N10276)
Hastelloy C-276 tube fittings are mechanical-grip compression fittings, machined from nickel alloy C-276 (UNS N10276, W.Nr. 2.4819). One or two ferrules swage onto the tube's outside diameter, forming a leak-tight, gas-tight seal along with a solid grip on the tube itself. That combination is what makes C-276 fittings the go-to for wet chlorine, hot acids, chloride, and sour-gas instrumentation lines. Crestflo carries these fittings from 1/8-inch through 2-inch (50 mm) tube OD, in both single and double (twin) ferrule versions. They're qualified to ASTM F1387 and offered to NACE MR0175 / ISO 15156 for sour service. Standard items ship from stock; specials are built to order, with delivery running 6-8 weeks. Request a quote to price out your configuration.
Hastelloy® is a registered trademark of Haynes International, Inc.
What Hastelloy C-276 Compression Tube Fittings Are
A Hastelloy C-276 compression tube fitting is built for fluid-system instrumentation work: a body, a nut, and one or two ferrules that bite into the tube's outer diameter as the nut is torqued down. The result is a joint you can take apart and put back together without losing integrity. No flaring, no welding, no elastomer seal in the leak path. The seal is metal-to-metal, so the joint's temperature ceiling comes from the alloy, not from an O-ring giving out first.
Scope matters here. These are instrumentation compression tube fittings in alloy C-276, not plumbing pipe fittings, and not electrical wire ferrules. They tie into small-bore instrument tubing on analyzers, transmitters, sample lines, chemical-injection systems, and process taps, wherever chlorides, H₂S, or aggressive acids push 316 stainless out of the running.
Also Known As: Alloy C-276, C276, UNS N10276, W.Nr. 2.4819
Buyers and specifiers write the same alloy several ways, but they all point to the same Ni-Mo-Cr-W material. "Hastelloy® C-276" is the trademarked designation. "Alloy C-276," "C-276," and "C276" are the common generic forms. The material is registered as UNS N10276 and Werkstoff 2.4819, with the ISO name NiMo16Cr15W. Fitting feedstock is covered by the wrought nickel-alloy specifications ASTM B574 (rod and bar) and ASTM B366 (wrought fittings, grade WPHC276).
| Designation type | Value |
|---|---|
| Common names | Hastelloy C-276, Alloy C-276, C-276, C276 |
| UNS number | N10276 |
| Werkstoff / EN | 2.4819 |
| ISO designation | NiMo16Cr15W |
| Wrought feedstock specifications | ASTM B574 (bar), B366 WPHC276 (wrought fittings) |
Because these names all point to the same product, asking for "alloy C-276 fittings," "N10276 tube fittings," or "2.4819 fittings" gets you exactly what's described on this page. The terms are interchangeable.
Why Choose Hastelloy C-276 for Instrumentation Tube Fittings
Hastelloy C-276 is a nickel-molybdenum-chromium-tungsten alloy that holds up in both oxidising and reducing media, a combination few alloys manage. The high molybdenum and tungsten content drive its resistance to pitting, crevice corrosion, and chloride stress-corrosion cracking, exactly the failure modes that limit austenitic stainless. Chromium handles the oxidising side. One more thing sets it apart: C-276 carries one of the lowest carbon and silicon limits of any wrought nickel alloy, which keeps corrosion resistance intact through welds and heat-affected zones. For a compression fitting that sees wet chlorine, hot contaminated HCl, ferric and cupric chlorides, or sour hydrocarbon streams, that chemistry is the whole point.
For the full metallurgical picture, composition ranges, mechanical and physical properties, PREN, and corrosion-by-media data, see the Hastelloy C-276 alloy grade page. We've summarized the reference composition below for convenience when writing specs. The values follow the applicable ASTM specification, and Crestflo verifies actual heat chemistry on the material test certificate.
| Element | wt % (per ASTM B574 / B366) |
|---|---|
| Nickel (Ni) | Balance (~57) |
| Molybdenum (Mo) | 15.0–17.0 |
| Chromium (Cr) | 14.5–16.5 |
| Iron (Fe) | 4.0–7.0 |
| Tungsten (W) | 3.0–4.5 |
| Carbon (C) | 0.010 max |
| Silicon (Si) | 0.08 max |
For a head-to-head against the alloys most often weighed against it, see Hastelloy C-22 for strongly oxidising duty, Inconel 625 where high-temperature strength governs, and the Hastelloy vs Inconel guide.
Hastelloy C-276 Tube Fitting Sizes (1/8-inch to 2-inch OD): Imperial & Metric
Crestflo machines Hastelloy C-276 tube fittings in both imperial fractional and metric tube-OD series, with end connections up to 2-inch (50 mm) OD. The size chart below covers the standard imperial and metric range. Working pressure for any given fitting depends on size, wall thickness, and temperature. It comes from standard tube-fitting pressure data for the tube OD and wall, following ASTM/ASME practice, and the exact rated pressure for your configuration is confirmed on the quotation. Values follow the applicable standard and can be customized to requirement.
| Tube OD, imperial | Tube OD, metric | Availability |
|---|---|---|
| 1/8", 1/4", 3/8", 1/2" | 6 mm, 8 mm, 10 mm, 12 mm | Standard range |
| 5/8", 3/4", 1" | 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 25 mm | Standard range |
| up to 2" (50 mm) | up to 50 mm | Made-to-order |
Hastelloy C-276 Tube Fitting End & Thread Connections: NPT, BSPP, JIC & Weld
Fittings come with tube-OD compression ends, tapered or parallel threads, or weld ends. All fittings are available in national, international, and custom thread types.
| End type | Thread / connection standards |
|---|---|
| Tube-OD (compression) | Fractional inch and metric OD |
| Male / female tapered thread | NPT, NPTF, BSPT |
| Male / female parallel thread | BSPP, ISO parallel, SAE ORB |
| Flare / port | JIC 37°, SAE ORB |
| Weld end | Socket-weld, butt-weld, orbital |
Single vs Double Ferrule & Hardened vs Non-Hardened Options
Hastelloy C-276 fittings come in single-ferrule and double (twin) ferrule designs, and hardened or non-hardened ferrules are supplied depending on what the job calls for. This choice shapes gripping action, vibration resistance, and how many times the fitting can be reassembled.
| Configuration | Description | When it is used |
|---|---|---|
| Double (twin) ferrule | Front ferrule seals, back ferrule grips | General instrumentation, vibration, gas-tight service |
| Single ferrule | One ferrule seals and grips | Simpler assemblies, certain hydraulic and OEM designs |
| Hardened ferrule | Case-hardened grip surface | Harder tube materials, maximum hold |
| Non-hardened ferrule | Softer grip surface | Thin-wall or softer tubing |
Replacement nuts and ferrules are stocked separately, and so are single-ferrule fittings. For the geometry range and ferrule design, start at the tube-fittings product hub.
Available Hastelloy C-276 Fitting Shapes & Connectors
Alloy C-276 covers the full geometry range, so you can build a complete instrument run in a single material:
- Union, elbow, tee, cross, and reducer fittings
- Male connectors, female connectors, and adapters for joining mismatched threads
- Bulkhead unions, port connectors, caps, and plugs for sealing off unused lines
- Weld connectors (socket, butt, and orbital)
C-276 comes in related fitting families too, including 37° JIC flare fittings and DIN 2353 bite-type fittings, all combinable within the same instrument tubing system.
Standards, Testing & NACE MR0175 Sour-Service Compliance
Crestflo qualifies its compression tube fittings to ASTM F1387, the performance standard for mechanically attached fittings. That's the basis for dimensional interchange and mechanical-integrity claims. For sour service, C-276 fittings are offered to NACE MR0175 / ISO 15156. In the solution-annealed condition, UNS N10276 is an accepted nickel-base corrosion-resistant alloy for sour (H₂S-containing) service under NACE MR0175 / ISO 15156-3; confirm the hardness and material-condition limits in the standard against your application. We hold the standard approvals that apply to instrumentation tube fittings.
| Standard / certification | Scope | Applies here |
|---|---|---|
| ASTM F1387 | Mechanically attached fitting performance | Yes |
| NACE MR0175 / ISO 15156 | Sour-service materials | Yes |
| EN 10204 MTC 3.1 / 3.2 | Material test certification | Yes |
| ASTM B574 / B366 | Nickel-alloy bar & wrought-fitting feedstock forms | As applicable |
| ISO 9001 / 14001 / 45001 & PED | Quality, environmental, safety, pressure | Certified |
These fittings go through a wide battery of tests. Hydraulic proof, burst, and impulse come first. Then there's pneumatic, flexure-fatigue, rotary-flex, vibration, and thermal-cycling work, plus pull-out and vacuum checks. Positive material identification (PMI) confirms the alloy on every piece, which matters for an exotic grade where substitution is a real risk. NDT is standard and done in-house. Destructive testing goes out to labs accredited under ISO/IEC 17025. Third-party inspection is available on request.
Material Traceability & Certification
Every Hastelloy C-276 part is marked with its own heat/lot number. Each shipment comes standard with an EN 10204 MTC 3.1 certificate, and 3.2 is available on request. PMI confirms grade at the part level, every time. That documentation backs solid audit trails for offshore, subsea, and sour-service work, the kind of jobs where a mis-specified alloy is not a small problem.
Drop-In Interchange with Swagelok, Parker & Hy-Lok
Crestflo Hastelloy C-276 fittings are built as dimensional interchange / equivalent fittings for the major instrumentation brands, and that claim rests on ASTM F1387 performance qualification, not on marketing language. These aren't "compatible" or "intermix" parts. Brand names such as Swagelok®, Parker®, and Hy-Lok® remain trademarks of their respective owners, and Crestflo is not affiliated with them; the interchange is strictly dimensional. We don't publish a part-number table. Instead, we prepare interchange references per project: request your cross-reference, and our engineering team will map your existing part numbers to Crestflo C-276 equivalents.
Origin & US-Serving Positioning
Crestflo manufactures for the US market. Standard product comes from India; US or European melt is available on request, with full material traceability. Parts are engineered as US drop-in replacements and ship in 6-8 weeks. TAA/DFARS and domestic-melt requirements are handled straight, no hedging, on our US-origin compliance page. If a project calls for a specific melt origin, just specify it on the RFQ.
Why Crestflo for Hastelloy C-276 Tube Fittings
Crestflo operates as the instrumentation division of an export house with four decades behind it and formal recognition from the Government of India. That parent company has a proven delivery record across the Middle East. Its backing grounds a new, focused instrumentation brand built on a handful of clear advantages:
- Lead time of 6-8 weeks versus 20+ weeks typical of the majors.
- ASTM F1387 drop-in interchange proof that mill and trading suppliers rarely publish.
- Small MOQ and private label for distributors and OEMs.
- Both imperial and metric on every fitting, single or double ferrule, hardened or non-hardened.
- Heat-number marking plus MTC 3.1/3.2 on every order, PMI-confirmed.
- Cost-competitive after US duties and tariffs, ISO 9001 / 14001 / 45001 & PED certified.
We Engineer Confidence.
Request a Quote for Hastelloy C-276 Fittings
Give us the details: size, shape, ferrule, thread, and quantity. We'll price it out and get your order scheduled:
- Request a quote, the fastest path to pricing and lead time.
- Request a sample for qualification.
- Become a distributor for line-card and stocking programs.
Datasheets and CAD models are available to customers on request. Reach Crestflo's US sales desk at sales@crestflousa.com or +1 346 594 9005 (Houston, TX). Round out your system with the related Hastelloy C-276 instrumentation valves and Hastelloy C-276 tubing, and serve the corrosion-critical lines in oil and gas and petrochemical and chemical plants.
Frequently Asked Questions
Are Alloy C-276 and Hastelloy C-276 the same?
Yes. "Alloy C-276," "C-276," and "Hastelloy® C-276" all point to the same material: UNS N10276, also listed as Werkstoff 2.4819, a nickel-molybdenum-chromium-tungsten alloy. Hastelloy® is a trademarked brand name held by Haynes International, Inc. Alloy C-276 and C276 are the generic designations for that same material.
What is the difference between Hastelloy C-276 and C-22 tube fittings?
Both are Ni-Mo-Cr corrosion-resistant Hastelloy grades, but C-276 is the broad workhorse for chemical service that swings between reducing and oxidising conditions, including wet chlorine, hot acids, and seawater. Hastelloy C-22 carries higher chromium, which suits strongly oxidising acid mixtures and hot oxidising chlorides better. For the full picture, see Hastelloy C-22.
How much do Hastelloy C-276 tube fittings cost?
As a high-nickel superalloy, C-276 fittings run more than stainless steel does, and the price shifts with size, shape, ferrule type, and quantity ordered. Crestflo stays cost-competitive even after US duties and tariffs, but it quotes per configuration. There's no live pricing posted anywhere. Request a quote to get a firm number.
What are Hastelloy C-276 tube fittings used for?
They handle corrosion-critical instrumentation lines wherever chlorides, H₂S, or aggressive acids rule out stainless: sour and offshore oil and gas, petrochemical and chemical processing, flue-gas desulfurization scrubbers, pulp-and-paper bleaching, and seawater or brackish-water service. C-276 holds up in both oxidising and reducing media.
Are Crestflo Hastelloy C-276 fittings NACE-compliant?
Yes. In the solution-annealed condition, UNS N10276 is an accepted nickel-base corrosion-resistant alloy for sour service under NACE MR0175 / ISO 15156-3. Crestflo offers C-276 fittings to that standard with material traceability backing project qualification; confirm the hardness and material-condition limits in the standard against your application.
Do they interchange with Swagelok, Parker, or Hy-Lok fittings?
They're built as dimensional interchange and equivalent fittings, with performance backed by ASTM F1387 qualification. We don't call them "compatible" or "intermix," and every brand name mentioned belongs to its respective owner; Crestflo is not affiliated. Send us your cross-reference request and we'll map your part numbers.
What sizes are available?
Tube-OD sizes run from 1/8-inch up to 2-inch (50 mm), covering both imperial fractional and metric series, in single or double ferrule. Standard sizes span 1/8" to 1" and 6 mm to 25 mm; anything larger is made to order.
Are single and double ferrule versions both offered?
Yes. Both single-ferrule and double (twin) ferrule designs are available, with hardened or non-hardened ferrules supplied depending on what's required.
What material certification comes with the fittings?
Standard practice is an EN 10204 MTC 3.1 certificate, though 3.2 is available if you ask for it. Every part gets a heat/lot number stamped on it, and PMI confirms the alloy is genuinely N10276.
Are these made in the USA?
Crestflo manufactures for the US market. Standard product comes from India, though US or European melt is available on request, complete with full material traceability. It's engineered for a US drop-in fit and ships in 6-8 weeks. For TAA and origin specifics, see the US-origin compliance page.
What thread and end connections are available?
Tube-OD compression ends come standard, alongside NPT, NPTF, BSPT, BSPP, and ISO parallel threads. JIC 37° and SAE ORB fittings round out the lineup, and weld ends are available in socket, butt, and orbital styles. National, international, or custom thread, they're all supported.
What is the minimum order and lead time?
Small minimum order quantities apply, and lead time for US orders runs 6 to 8 weeks. Standard items ship from ready stock; specials are made to order. Private-label and custom or made-to-print options are also available.