Hastelloy C-276 Buttweld Pipe Fittings
Hastelloy C-276 / UNS N10276 / EN 2.4819 (NiMo16Cr15W) — 15Cr-16Mo-4W nickel-molybdenum-chromium alloy for the most aggressive chemical environments: HCl at all concentrations, wet chlorine, mixed acids, H2SO4, and FGD scrubber service. PRE >50. FGD, chemical process, pharmaceutical, pulp & paper. ASME B16.9 and EN 10253-2 Type B. EN 10204 3.1 standard; 3.2 TPI on request.
½″–24″
Size Range
PRE >50
Pitting Index
690 MPa
Min UTS (Annealed)
HCl 0–100%
All Conc.
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Hastelloy C-276 Grade Equivalents
| Trade Name | UNS | EN W.Nr. | EN Name | ASME P-No. |
|---|---|---|---|---|
| Hastelloy C-276 | N10276 | 2.4819 | NiMo16Cr15W | 44 |
| Alloy C-276 (generic) | N10276 | 2.4819 | NiMo16Cr15W | 44 |
'Hastelloy' is a registered trademark of Haynes International. Covered by ASTM B366 (welded/wrought fittings), ASTM B574 (rod/bar), ASTM B575 (plate).
Chemical Composition — C-276 / N10276 / EN 2.4819
| Element | Specification |
|---|---|
| Ni | Balance (min ~57%) |
| Mo | 15.0–17.0% |
| Cr | 14.5–16.5% |
| W | 3.0–4.5% |
| Fe | 4.0–7.0% |
| Co | ≤2.5% |
| C | ≤0.010% |
Ultra-low carbon (C ≤0.010%) and tungsten (W) addition give C-276 its exceptional corrosion resistance. Low C prevents sensitization — no PWHT required in most fabrications. ASME P-No. 44.
Mechanical Properties — C-276 (Annealed)
| Property | Min. UTS | Min. YS | Elongation | Max Service Temp |
|---|---|---|---|---|
| Annealed (ASTM B366) | 690 MPa | 283 MPa | ≥40% | 1040°C (oxidising, short-term) 760°C continuous |
Welding & PWHT — Hastelloy C-276
✓ No PWHT Required
Hastelloy C-276 does not require post-weld heat treatment in most fabrication applications. The ultra-low carbon content (≤0.010%) prevents sensitization of the heat-affected zone. Annealing after severe forming is recommended.
Filler Metal
ERNiCrMo-4 (C-276 matching filler) for GTAW/GMAW. Matching composition is critical to maintain corrosion performance.
Preheat
No preheat required for normal thickness. Material should be at ambient temperature or slightly warm — avoid cold joints in winter conditions.
Inter-pass Temperature
Maximum 150°C. Low heat input is essential to minimise HAZ width and preserve corrosion resistance.
Heat Input
Low heat input. Maintain stringer beads where possible. Avoid weaving. Back purge with argon for root passes in critical corrosive applications.
C-276 vs Other Corrosion-Resistant Alloys
| Grade | Mo% | Key Strength | Weakness |
|---|---|---|---|
| 316L (1.4404) | 2.2% | Cost | HCl, H2SO4 |
| 904L (1.4539) | 4.5% | H2SO4, phosphoric | Limited HCl |
| Inconel 625 (N06625) | 9% | Seawater, sour gas, high temp | Reducing acids |
| Hastelloy C-276 (N10276) | 16% | HCl, mixed acids, FGD | Higher cost |
Hastelloy C-276 Fitting Types
90° Long Radius Elbows
ASME B16.9 / EN 10253-2 Type B. R=1.5D. ½″–24″ all schedules.
45° Long Radius Elbows
ASME B16.9 / EN 10253-2 Type B. Low-turbulence direction change for corrosive media.
Equal Tees
ASME B16.9 / EN 10253-2 Type B. Branch connections for HCl, mixed acid piping systems.
Reducing Tees
ASME B16.9. Unequal branch configurations for process piping.
Concentric Reducers
ASME B16.9 / EN 10253-2. Centreline maintained for horizontal runs.
Eccentric Reducers
ASME B16.9 / EN 10253-2. Flat-bottom configuration for pump suction, drainage.
Pipe Caps
ASME B16.9. Ellipsoidal end closure for line termination and hydro test blanking.
180° Returns
ASME B16.9 Long Radius. U-bend configurations for heat exchanger piping.
Stub Ends (Lap Joint)
ASME B16.9. For lap joint flanges — allows rotation to align bolt holes in corrosive service.
Industries & Applications
HCl Production & Handling
Hastelloy C-276 is the benchmark alloy for hydrochloric acid at all concentrations and temperatures, where stainless steels fail rapidly. Specified for HCl synthesis columns, absorption towers, and transfer piping.
FGD Scrubbers
Flue gas desulphurisation systems handling hot SO2-laden gases and chloride-containing slurries. C-276 resists the combined attack of sulphuric and hydrochloric acids in FGD environments.
Wet Chlorine Service
Chlorine gas in the presence of moisture is among the most corrosive environments. C-276 provides reliable performance in chlorine handling, bleach production, and chlorinated solvent plants.
Mixed Acid Plants
Nitration, sulphation, and mixed-acid processes in chemical manufacturing. C-276's combination of Ni, Mo, Cr, and W resists the synergistic attack of multiple acid streams.
Pharmaceutical API Synthesis
Active pharmaceutical ingredient manufacturing involves chlorinated solvents, HCl gas, and aggressive reaction conditions. C-276 meets purity and corrosion requirements for GMP-compliant plants.
Waste Acid Recovery
Regeneration plants handling spent acids, particularly mixed HCl/H2SO4/HF streams from pickling, etching, and surface treatment operations. C-276 outperforms all stainless and duplex grades in these conditions.
Frequently Asked Questions
What is Hastelloy C-276 used for in pipe fittings?
Hastelloy C-276 (UNS N10276, EN 2.4819, NiMo16Cr15W) is specified for the most aggressive chemical environments where stainless steels and even other Ni alloys fail. Its very high Mo content (15–17%) gives exceptional resistance to reducing acids — particularly hydrochloric acid (HCl) at all concentrations, sulphuric acid, mixed acids, and wet chlorine gas. Principal industries: chemical process (HCl production and handling, chlorinated solvents), pharmaceutical API synthesis, FGD (flue gas desulphurisation) scrubbers, waste acid recovery, acetic acid plants, pulp & paper. C-276 is also characterised by very high resistance to pitting and crevice corrosion (PRE >50) and good resistance to chloride SCC.
What is the difference between Hastelloy C-276 and Inconel 625 for corrosive service?
C-276 (N10276, 16Cr-16Mo-4W, no Nb) has higher Mo than Inconel 625 (N06625, 22Cr-9Mo-3.5Nb), making C-276 superior for reducing acid environments — especially HCl, wet chlorine, and mixed reducing/oxidizing acids. Inconel 625 has higher Cr and Nb, giving better oxidising acid resistance and higher strength at elevated temperatures. For seawater and sour gas injection, both perform well but 625 is more commonly specified. For chemical plants with HCl or mixed-acid service, C-276 is the preferred choice. Both have PRE >50 and similar cost levels.
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Specify size, schedule, fitting type, standard (ASME B16.9 or EN 10253-2 Type B), and required MTR. EN 10204 3.1 standard, 3.2 TPI available. We respond within 1 business day.
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