Hastelloy C-276 Tubing (UNS N10276)

Hastelloy C-276 tubing is OD-sized, round instrumentation tube drawn from nickel alloy C-276 (UNS N10276, W.Nr. 2.4819), a nickel-molybdenum-chromium-tungsten corrosion-resistant grade. It carries process fluid or gas between components and seats into a compression fitting's ferrule set to make a leak-tight, make-and-break joint. Crestflo supplies C-276 tube seamless to ASTM B622 and welded-and-drawn to ASTM B626, in both imperial and metric sizes, shipped in the solution-annealed condition so it bends and cones cleanly into a ferrule. You reach for C-276 tube when the line runs wet chlorine, hot contaminated acid, ferric and cupric chlorides, or sour gas loaded with H₂S, CO₂, and chlorides, the service where 316 stainless, and often duplex too, pits, cracks, or thins out. Standard items ship from stock; specials are built to order, with delivery running 6-8 weeks. Request a quote to price your run.

Reviewed by the Crestflo Engineering Team

Hastelloy® is a registered trademark of Haynes International, Inc. Swagelok® and Parker® are trademarks of their respective owners; Crestflo is not affiliated, and interchange is dimensional.

Why Specify Hastelloy C-276 Tubing

Tube is the long, continuous wetted surface of an instrument hookup. Unlike a fitting or a valve, it has no dead legs or packing bores, but it has length, every inch of it exposed to the media, and it has to survive the cold work of bending and ferrule make-up without cracking. On a corrosive line that rules out a lot of materials. A stainless tube that pits or stress-corrosion cracks midway along a run is as dead as one that fails at the fitting.

Hastelloy C-276 is a nickel-molybdenum-chromium-tungsten alloy that resists both oxidising and reducing media, a combination few metals manage. The high molybdenum and tungsten drive its resistance to pitting, crevice corrosion, and chloride stress-corrosion cracking; the chromium handles the oxidising side. For a tube run carrying wet chlorine, hot impure HCl or H₂SO₄, ferric and cupric chlorides, seawater, or sour wellhead fluid, that chemistry is the whole reason to pay the alloy premium. Where 316 and even 2205/2507 duplex tube pit or crack, a C-276 tube keeps its wall and keeps sealing at every joint along the line.

The full metallurgical picture, composition ranges, mechanical and physical properties, PREN, and corrosion-by-media data, lives on the Hastelloy C-276 alloy grade page. This page stays on the tube: how it's made, sized, finished, tested, and matched to the fitting.

Also Specified As: Alloy C-276 Tube, C276 Seamless Tubing, UNS N10276 Tube

Buyers and specifiers call this tube several ways, and each one points to the same Ni-Mo-Cr-W material. A requisition might read "Alloy C-276 tubing," "C276 seamless tube," "N10276 instrument tube," "Hastelloy C276 hydraulic tubing," or "NiMo16Cr15W tube," and every one of them lands here. Hastelloy® C-276 is the trademarked designation; Alloy C-276, C-276, and C276 are the generic forms; the material is registered as UNS N10276 and Werkstoff 2.4819, ISO name NiMo16Cr15W. The welded form is often written "welded-and-drawn tube," the seamless form "cold-drawn seamless tube."

Scope: this is round, OD-sized instrumentation and fluid-system tube for compression and tube-fitting connections. It is not oilfield coiled tubing for downhole well intervention, not structural or ornamental tube, and not pipe specified by nominal pipe size (NPS) and schedule. Crestflo supplies C-276 in instrumentation tube, fitting, and valve forms only, not mill bar, sheet, plate, or pipe.

Seamless vs Welded Hastelloy C-276 Tubing

Both constructions are built to their own nickel-alloy tube standard, and both accept a compression fitting the same way. Seamless C-276 tube is cold-drawn from a hollow with no longitudinal weld, which makes it the default where you want maximum integrity for higher-pressure, cyclic, or critical sour service. Welded-and-drawn C-276 tube is formed from strip, seam-welded, then cold-drawn to size; it is dimensionally consistent and cost-effective for general instrument and fluid-system work. The grade's very low carbon and silicon limits (C 0.010% max, Si 0.08% max) are what keep corrosion resistance intact in the weld and the heat-affected zone, which is why welded-and-drawn C-276 holds up in service that would sensitise a leaner alloy.

Not sure which construction to call out? The deep dives on seamless tubing and welded tubing walk through the trade-off before you commit a spec.

Hastelloy C-276 Tube Attributes at a Glance

Hastelloy C-276 Tube Sizes: OD, Wall & Imperial/Metric

Instrument tube is specified by its actual outside diameter and wall thickness, given in both imperial and metric units, never by NPS and schedule. The common instrument range runs fractional 1/8″ to 1″ and metric 6 to 12 mm; smaller 1/16″ small-bore tube and larger diameters up to 2″ (50 mm) are available to order. Wall thickness is chosen to carry the pressure and to suit the ferrule, and both OD and wall are held to the tolerances of ASTM B622 (seamless) or B626 (welded). Working pressure is not a single blanket figure: it is calculated from OD, wall thickness, and the alloy's allowable stress per ASME B31.3, so it is stated per size and wall rather than as one rating for the grade.

Values per applicable standard; customizable to requirement. For how to work back from a target pressure to a wall thickness, see the tube sizing and wall thickness guide, and for the full dimensional matrix across the range, the tubing size chart.

Temper & Hardness: Solution-Annealed for Bending and Ferrule Seating

The single most important mechanical property of instrument tube is not its strength but its softness. C-276 tube ships in the solution-annealed condition, and that matters for two reasons. First, it is what lets the tube bend around a radius and cone down under a ferrule without cracking, so the joint seats and seals the way a compression fitting is designed to. Second, the solution-annealed condition is the one NACE MR0175 / ISO 15156-3 accepts for UNS N10276 in sour service, so the temper that makes the tube workable is also the temper that makes it qualified. In the solution-annealed condition C-276 still carries high strength, a tensile minimum around 100 ksi (690 MPa) with a 0.2% yield near 41 ksi (283 MPa), while staying ductile and tough from cryogenic temperatures up through its service range. Specify the hardness or condition to your own standard on the RFQ and it is confirmed on the certificate.

Finishes & Cleanliness: Bright-Anneal, Electropolish & Oxygen-Clean

C-276 tube ships in a mill/bright-annealed finish as standard. For high-purity gas, analytical, and oxygen service, passivation, electropolishing (EP), and oxygen/UHP cleaning with capped-and-bagged packaging are available. Electropolishing lowers surface roughness and smooths the inner diameter, which matters where particle generation, moisture dry-down, or deposit build-up is the concern. Standard UHP electropolish surface-roughness targets can be specified right on the RFQ to your own standard; electropolished tubing and oxygen and UHP cleaning cover the options in detail. Finish and cleanliness figures follow the applicable standard and are customizable to requirement.

Hastelloy C-276 Tube Standards: ASTM B622, B626 & ASME B31.3

C-276 tube is covered by the nickel-alloy tube specifications, not the austenitic-stainless ones, and the construction decides which applies: seamless falls under ASTM B622, welded under ASTM B626, each with its matching ASME boiler-code SB- designation. Allowable working pressure for a given size and wall is calculated per ASME B31.3. For sour service, the material is offered to NACE MR0175 / ISO 15156. Crestflo holds the standard approvals that apply to instrumentation tube and is ISO 9001 / 14001 / 45001 and PED certified.

Working Pressure: Calculated per ASME B31.3, Not Assumed

There is no single pressure rating for "C-276 tube," and any supplier who quotes one is skipping the engineering. Allowable internal pressure depends on three things: the tube OD, its wall thickness, and the alloy's allowable stress at the service temperature. ASME B31.3 sets the method, relating wall thickness to pressure, diameter, the allowable stress value S, the weld-joint quality factor E, and the coefficient Y. Seamless tube carries a higher joint factor than welded, which is part of why seamless is chosen for higher-pressure work. Because C-276 holds strength well above room temperature, its allowable stress derates more gently than austenitic stainless as the line heats up, an advantage on hot acid and sour service. Give us the OD, wall, temperature, and medium on the RFQ and the engineering team returns the calculated working pressure for your configuration. Values per the applicable standard; customizable to requirement.

Testing, NDT & NACE MR0175 Sour-Service Compliance

Every length of C-276 tube is verified before it ships. ASTM B622 and B626 require each tube to pass either a hydrostatic test or a nondestructive (eddy-current) electric test, and dimensional checks confirm OD, wall, and straightness against the ordered tolerances. Positive material identification (PMI) confirms the alloy on the material, which matters for an exotic grade where substitution is a real and costly risk. NDT is done in-house; destructive testing, where a job calls for it, goes to ISO/IEC 17025-accredited labs, and third-party inspection is available on request.

For sour service, C-276 tube material is 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) environments under NACE MR0175 / ISO 15156-3. Confirm the hardness and material-condition limits in the standard against your application, and note the sour-service requirement on the RFQ.

Straight Lengths & Coiled Hastelloy C-276 Tube

C-276 tube ships as straight lengths for racked and rigidly supported runs, and as continuous coils for heat-tracing, long analyzer and sample lines, and umbilical and hydraulic bundles where a joint-free run is the whole point. Coiled tube keeps the count of mechanical joints down, which on a corrosive or buried line is one fewer place to leak. Both forms are supplied solution-annealed; call out length or coil length on the RFQ. For long-run and tracing applications, see coiled tubing; for thicker-wall high-pressure control lines, hydraulic tubing.

Material Traceability & Certification

Every length of Hastelloy C-276 tube carries its own heat/lot number, and each order ships with an EN 10204 MTC 3.1 certificate as standard, 3.2 available on request. PMI confirms the grade at the part level, every time. That documentation backs the audit trails that offshore, subsea, and sour-service jobs demand, the kind of work where a mis-specified tube in a long run is an expensive thing to discover in commissioning. Full detail is on the traceability page.

Applications for Hastelloy C-276 Tubing

C-276 tube earns its place wherever chlorides, H₂S, or aggressive acids rule stainless and duplex out of a long wetted run:

• Sour upstream and offshore oil & gas, wellhead, platform, and subsea instrument and chemical-injection lines in H₂S + CO₂ + chloride service, where NACE MR0175 governs the material. See the oil & gas industry page.
• Hydraulic and chemical-injection umbilicals, long coiled runs where a corrosion failure mid-bundle is unrecoverable.
• Acid and chemical processing, hot contaminated HCl, H₂SO₄, and organic-acid streams on analyzer, sample, and dosing lines.
• Flue-gas desulfurization (FGD), scrubber and absorber instrument lines in wet, chloride-laden gas.
• Seawater and brackish-water service, chloride pitting and crevice environments on offshore and coastal plant.
• Pharmaceutical and fine-chemical, corrosive batch processes needing a clean, traceable, electropolishable alloy tube.

Pairing C-276 Tube With C-276 Fittings and Valves

A tube is one part of the hookup, and the joint is only as corrosion-resistant as its weakest metal. For a matched instrument run, pair this tube with Hastelloy C-276 tube fittings and Hastelloy C-276 instrumentation valves so the whole assembly, tube, ferrules, and valve body, carries the same resistance and the same traceability. Crestflo supplies the tube alongside compression fittings tested to ASTM F1387, so the ferrule set seats correctly on the exact OD and wall you ordered, and the joint is a dimensional match rather than a mix of two suppliers' tolerances. Putting a C-276 tube into a 316 fitting just moves the failure point to the ferrule.

Drop-In Interchange and the Tube-Plus-Fitting System

Crestflo C-276 tube is cut and finished to standard OD and wall, so it drops into the compression fittings you already run, and the matching C-276 fittings are built as dimensional interchange / equivalent parts for the major brands, with the fitting ends qualified to ASTM F1387. These are not "compatible" or "intermix" parts. Swagelok® and Parker® remain trademarks of their respective owners, and Crestflo is not affiliated; the interchange is strictly dimensional. Moving a run off a major brand? Request your Swagelok®/Parker® cross-reference and the engineering team maps your tube and fitting part numbers to Crestflo C-276 equivalents. We don't publish a part-number table.

Origin & US-Serving Positioning

Crestflo manufactures for the US market. Standard product is of Indian origin; US or European melt is available on request, with full material traceability. Tube is engineered as a US drop-in and ships in 6-8 weeks, well under the 20+ weeks typical of the majors. If a project calls for a specific melt origin or TAA/DFARS handling, specify it on the RFQ and we'll address it straight, no hedging. See the US-origin compliance page for how we document it.

Why Crestflo for Hastelloy C-276 Tubing

Crestflo operates as the instrumentation division of an export house with four decades behind it and formal recognition from the Government of India, with a proven Middle-East delivery record. That backing grounds a focused instrumentation brand built on a handful of clear advantages:

• Lead time of 6-8 weeks versus 20+ weeks typical of the majors, on standard stock and made-to-order specials alike.
• A matched system, tube plus F1387-tested fittings and ferrules that seat on the exact OD and wall you ordered.
• Both seamless and welded C-276 tube, in both imperial and metric, straight or coiled.
• Heat-number marking plus MTC 3.1/3.2 on every order, PMI-confirmed, so an exotic grade is never taken on trust.
• NACE MR0175 / ISO 15156 material options for sour service, in the solution-annealed condition.
• ISO 9001 / 14001 / 45001 & PED certified, cost-competitive after US duties and tariffs, with small MOQs and private-label available.

We Engineer Confidence.

Request a Quote for Hastelloy C-276 Tubing

Give us the details: seamless or welded, OD and wall, straight length or coil, finish and cleanliness, and the line conditions (media, pressure, temperature, sour-service requirement). We'll calculate the working pressure, confirm the spec, and schedule the run.

• Request a quote, the fastest path to pricing and lead time.
• Request a sample for qualification.
• Request your Swagelok®/Parker® cross-reference and we'll map your tube and fitting part numbers.

Datasheets and CAD 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 the system with C-276 tube fittings and C-276 valves, browse the tubing pillar for other grades and constructions, and see where this tube serves in sour and offshore oil & gas.

Frequently Asked Questions

Related Pages

• Hastelloy C-276 alloy grade & corrosion data
• Hastelloy C-276 tube fittings · Hastelloy C-276 instrumentation valves
• Tubing pillar · Instrumentation tubing · Seamless tubing · Welded tubing
• ASME B31.3 · NACE MR0175 · EN 10204 MTC · Oil & gas industry