Inconel 825 Buttweld Pipe Fittings
Incoloy 825 / UNS N08825 / EN 2.4858 (NiCr21Mo) — a 42Ni-21Cr-3Mo-Cu-Ti alloy engineered for sulphuric and phosphoric acid service. Copper for acid resistance, molybdenum and chromium for pitting and oxidising media, titanium stabilisation against sensitization. Used in acid processing, sour gas and nuclear reprocessing. ASME B16.9 and EN 10253-2 Type B. EN 10204 3.1/3.2.
½″–24″
Size Range
PRE ~30
Pitting Index
520 MPa
Min UTS (Annealed)
EN 10204
3.1 Std / 3.2 On Req.
Request Inconel 825 Quote
Response within 1 business day
Inconel 825 Grade Equivalents
| Trade Name | UNS | EN W.Nr. | EN Name | ASTM (fittings) | ASME P-No. |
|---|---|---|---|---|---|
| Incoloy 825 | N08825 | 2.4858 | NiCr21Mo | ASTM B366 / B564 | 45 |
| Inconel 825 / Alloy 825 | N08825 | 2.4858 | NiCr21Mo | ASTM B366 UNS N08825 | 45 |
"Incoloy" and "Inconel" are registered trademarks of Special Metals Corporation. EN designation 2.4858 / NiCr21Mo. Covered by ASTM B366 for welded fittings and ASTM B564 for forgings.
Chemical Composition — UNS N08825 / EN 2.4858
| Element | Specification |
|---|---|
| Ni | 38.0–46.0% |
| Cr | 19.5–23.5% |
| Mo | 2.5–3.5% |
| Cu | 1.5–3.0% |
| Fe | ≥22.0% (balance) |
| Ti | 0.6–1.2% |
| C | ≤0.05% |
Copper + titanium — copper delivers the alloy's characteristic resistance to sulphuric and phosphoric acids, while titanium ties up carbon as TiC to prevent sensitization during welding. No PWHT required.
Mechanical Properties — Inconel 825 (Annealed)
| Min. UTS | Min. YS | Elongation | Hardness | Max Continuous Service |
|---|---|---|---|---|
| 520 MPa | 220 MPa | ≥30% | ≤ 90 HRB | ~540°C |
Supplied in the solution-annealed and stabilised condition for buttweld fittings. Titanium stabilisation maintains intergranular corrosion resistance in the as-welded condition.
Welding & Post-Weld Heat Treatment
No PWHT Required
Titanium stabilisation prevents chromium-carbide precipitation, so Incoloy 825 maintains its corrosion resistance in the as-welded condition without post-weld heat treatment. Solution annealing at 920–980°C may be specified after severe cold work.
Recommended Filler
ERNiFeCr-1 (AWS A5.14) — Alloy 65 / FM 82-type matching filler for GTAW and GMAW of N08825.
Preheat
No preheat required. Nickel alloys do not suffer hydrogen cracking. Clean joints thoroughly to remove oils, grease and sulphur-bearing compounds before welding.
Inter-pass Temperature
≤150°C maximum. Use low heat input and stringer beads to preserve corrosion resistance in the weld and HAZ.
ASME P-Number
P-No. 45 (Ni-Fe-Cr alloys). Separate WPS required — cannot be qualified under austenitic SS procedures.
Alloy Selection Guide — Inconel 825 vs Alternatives
| Grade | PRE | Key Advantage | Typical Use |
|---|---|---|---|
| 316L / 1.4404 | ~24 | Cost | General chemical |
| 904L / 1.4539 | ~35 | Sulphuric acid (SS) | Acid, FGD |
| Inconel 825 / N08825 | ~30 | Sulphuric/phosphoric acid + sour | Acid process, sour gas |
| Inconel 625 / N06625 | >50 | Seawater + severe sour | Subsea, deep sour |
Key Application Areas
Sulphuric Acid Service
The copper addition gives excellent resistance across a wide range of sulphuric acid concentrations — pickling lines, acid evaporators and storage.
Phosphoric Acid Production
Resists wet-process phosphoric acid with chloride and fluoride impurities in fertiliser and chemical plants.
Sour Gas (NACE MR0175)
Resistant to H₂S-induced cracking for oil and gas production and sour-service piping to NACE MR0175 / ISO 15156.
Pickling & Acid Cleaning
Handles mixed sulphuric/nitric pickling baths and acid-cleaning circuits in metal processing.
Nuclear Fuel Reprocessing
Used in nitric-acid fuel reprocessing and radioactive-waste handling circuits.
Pollution Control
FGD and scrubber components handling acidic chloride condensates.
Available Fitting Types — Inconel 825 / UNS N08825
Sizes typically ½″–24″ for nickel alloys due to material cost and availability. Larger sizes available on enquiry with extended lead time.
Elbows — 90° & 45°
Long Radius (1.5D) and Short Radius (1D). ASME B16.9 / EN 10253-2 Type B. ½″–24″.
180° Return Bends
Long Radius. ASME B16.9. ½″–12″.
Equal & Reducing Tees
ASME B16.9 / EN 10253-2 Type B. ½″–24″.
Concentric & Eccentric Reducers
ASME B16.9 / EN 10253-2 Type B. ½″–24″.
Pipe Caps
ASME B16.9 / EN 10253-2 Type B. ½″–24″.
Lap Joint Stub Ends
ASME B16.9 Type A & B. ½″–16″. Paired with backing flanges to reduce cost.
Crosses (4-Way)
ASME B16.9. ½″–8″.
Laterals (45° Y)
ASME B16.9. ½″–8″.
Flanges — All Types
Weld Neck, Slip-On, Blind, Socket Weld, RTJ. ASME B16.5. ASTM B564 UNS N08825. ½″–24″.
Ready to order Inconel 825 fittings?
Specify size, schedule, fitting type, standard (ASME B16.9 or EN 10253-2 Type B), and required MTR level (EN 10204 3.1 or 3.2 TPI). NACE MR0175 documentation available on request.
Request a Quote →