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Incoloy 825 Flanges Supplier in Mumbai – ASTM B564 UNS N08825
Nicorex Alloys is an ISO 9001 / ISO 14001 certified supplier and stockist of Incoloy 825 flanges in Mumbai, India. We provide these Alloy 825 flanges in compliance with the ASTM B564 / ASME SB564.
Incoloy 825 (UNS N08825, Werkstoff 2.4858) is a titanium-stabilised nickel-iron-chromium-molybdenum-copper alloy. The composition consists of ~42% Ni, ~21.5% Cr, ~30% Fe, ~3% Mo, ~2% Cu, and ~0.9% Ti. What makes Alloy 825 unique is its dual acid resistance: copper at 1.5–3.0% handles reducing acids (sulfuric, phosphoric), while chromium at 19.5–23.5% resists oxidising acids (nitric). This makes Incoloy 825 flanges the standard forged piping connection for mixed-acid chemical processing environments where a single alloy must resist both acid types simultaneously. Titanium at 0.6–1.2% stabilises carbon as TiC, preventing chromium carbide precipitation (sensitisation) in the weld heat-affected zone. Flanges retain full corrosion resistance as-welded without post-weld heat treatment. Molybdenum at 2.5–3.5% adds pitting and crevice corrosion resistance in chloride-bearing media. It has a minimum tensile strength of 586 MPa (85 ksi), a yield strength of 241 MPa (35 ksi), and an elongation of 30%. At 42% Ni (vs 58% in Inconel 625), Alloy 825 delivers acid resistance at roughly half the cost per kilogram of full-nickel alloys.
The available types are WNRF, BLRF, SORF, SWRF, threaded, lap joint, and RTJ. Sizes range from NPS 1/2” to 24” (ASME B16.5); NPS 26” to 60” (B16.47). Classes cover 150 to 2500. Key industries these flanges serve include phosphoric acid production, sulfuric acid plants, sour gas handling per NACE MR0175, seawater cooling systems, FGD scrubbers, and pollution control.
Incoloy 825 Flanges Specifications
Forged flange specifications for UNS N08825 like standard, dimensions, types, and conditions are covered in the table below:
| Specification | ASTM B564 / ASME SB564 |
|---|---|
| Dimensional Standards | ASME B16.5, B16.47, MSS SP-44, DIN 17750, EN 1092-1, JIS B2220 |
| Size (ASME B16.5) | NPS 1/2” to NPS 24” |
| Size (ASME B16.47) | NPS 26” to NPS 60” |
| Pressure Classes | 150, 300, 600, 900, 1500, 2500 |
| Face Types | RF, FF, RTJ |
| Flange Types | WNRF, BLRF, SORF, SWRF, Threaded, Lap Joint, RTJ |
Chemical Composition of Incoloy 825 Flanges
The chemical composition of Incoloy 825 flanges as per ASTM B564 for UNS N08825 and its key alloying elements are covered below:
| Element | Nickel (Ni) | Chromium (Cr) | Iron (Fe) | Molybdenum (Mo) | Copper (Cu) | Titanium (Ti) | Carbon (C) | Manganese (Mn) | Silicon (Si) | Sulfur (S) | Aluminium (Al) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Wt% | 38.0 – 46.0 | 19.5 – 23.5 | 22.0 min (balance) | 2.5 – 3.5 | 1.5 – 3.0 | 0.6 – 1.2 | 0.05 max | 1.0 max | 0.5 max | 0.03 max | 0.2 max |
Copper (1.5–3.0%) is the element that separates 825 from standard Ni-Cr-Fe alloys. It improves resistance to sulfuric and phosphoric acid at production concentrations. Titanium (0.6–1.2%) stabilises the alloy by forming TiC, preventing Cr₂₃C₆ precipitation at grain boundaries during welding. Mo at 2.5–3.5% adds pitting and crevice resistance in chloride-bearing fluids.
Mechanical Properties of Incoloy 825 Flanges
As per ASTM B564, the mechanical properties of Alloy 825 flanges in the annealed condition are provided below:
| Property | Tensile Strength (min) | Yield 0.2% Offset (min) | Elongation (min) |
|---|---|---|---|
| Value | 586 MPa (85 ksi) | 241 MPa (35 ksi) | 30% |
Incoloy 825 has higher room-temperature strength than Incoloy 800H (586 vs 450 MPa tensile) because it does not require coarse grain for creep. The alloy is designed for corrosion service at moderate temperatures (up to 540°C), not high-temperature creep. Density is 8.14 g/cm³ (0.294 lb/in³). Melting range is 1370–1400°C (2500–2550°F).
Incoloy 825 Equivalent Grades
The standard equivalent designation of Incoloy 825 is UNS N08825, and its Werkstoff Nr. is 2.4858. Other international designations are listed in the table below
| UNS | Werkstoff | EN | DIN | JIS | AFNOR | GOST |
|---|---|---|---|---|---|---|
| N08825 | 2.4858 | NiFe30Cr21Mo3 | 17750, 17751, 17752 | NCF 825 | NC21FeDu | ХН38ВТ |
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Available Types of Incoloy 825 Flanges
All standard forged flange types per ASTM B564, focused on acid-handling and chemical processing service:
Incoloy 825 Weld Neck Flange (WNRF)
Incoloy 825 Blind Flange (BLRF)
Incoloy 825 Socket Weld Flange (SWRF)
Incoloy 825 RTJ Flange
Incoloy 825 Slip-On Flange (SORF)
Incoloy Alloy 825 Threaded Flange
Inconel 825 Lap Joint Flange
Nickel Alloy 825 Orifice Flange
Alloy 825 Spectacle Blind Flange
Inconel 825 Reducing Flange
Pressure-Temperature Ratings for Incoloy 825 Flanges
The table below shows the maximum working pressure (in bar and psig) that Incoloy 825 flanges can handle at different temperatures across Class 150 to Class 2500, as specified in ASME B16.5.
| Temp. °C (°F) | Class 150 bar (psig) | Class 300 bar (psig) | Class 400 bar (psig) | Class 600 bar (psig) | Class 900 bar (psig) | Class 1500 bar (psig) | Class 2500 bar (psig) |
|---|---|---|---|---|---|---|---|
| −29 to 38 (−20 to 100) | 20.0 (290) | 51.7 (750) | 68.9 (1000) | 103.4 (1500) | 155.1 (2250) | 258.6 (3750) | 430.9 (6250) |
| 50 (122) | 19.5 (283) | 51.7 (750) | 68.9 (1000) | 103.4 (1500) | 155.1 (2250) | 258.6 (3750) | 430.9 (6250) |
| 100 (212) | 17.7 (257) | 51.5 (747) | 68.7 (997) | 103.0 (1494) | 154.6 (2243) | 257.6 (3736) | 429.4 (6228) |
| 150 (302) | 15.8 (229) | 50.3 (730) | 66.8 (970) | 100.3 (1455) | 150.6 (2185) | 250.8 (3640) | 418.2 (6070) |
| 200 (392) | 13.8 (200) | 48.3 (700) | 64.5 (930) | 96.7 (1395) | 145.0 (2095) | 241.7 (3490) | 402.8 (5820) |
| 250 (482) | 12.1 (175) | 46.3 (665) | 61.7 (885) | 92.7 (1330) | 139.0 (1995) | 231.8 (3325) | 386.2 (5540) |
| 300 (572) | 10.2 (148) | 42.9 (605) | 57.0 (805) | 85.7 (1210) | 128.6 (1815) | 214.4 (3025) | 357.1 (5040) |
| 325 (617) | 9.3 (135) | 41.4 (590) | 55.0 (785) | 82.6 (1175) | 124.0 (1765) | 206.6 (2940) | 344.3 (4905) |
| 350 (662) | 8.4 (122) | 40.3 (570) | 53.6 (755) | 80.4 (1135) | 120.7 (1705) | 201.1 (2840) | 335.3 (4730) |
| 375 (707) | 7.4 (107) | 38.9 (530) | 51.6 (710) | 77.6 (1065) | 116.5 (1595) | 194.1 (2660) | 323.2 (4430) |
| 400 (752) | 6.5 (94) | 36.5 (510) | 48.9 (675) | 73.3 (1015) | 109.8 (1525) | 183.1 (2540) | 304.9 (4230) |
| 425 (797) | 5.5 (80) | 35.2 (485) | 46.5 (650) | 70.0 (975) | 105.1 (1460) | 175.1 (2435) | 291.6 (4060) |
| 450 (842) | 4.6 (67) | 33.7 (450) | 45.1 (600) | 67.7 (900) | 101.4 (1350) | 169.0 (2245) | 281.8 (3745) |
| 475 (887) | 3.7 (54) | 31.7 (385) | 42.3 (515) | 63.4 (775) | 95.1 (1160) | 158.2 (1930) | 263.9 (3220) |
| 500 (932) | 2.8 (41) | 28.2 (365) | 37.6 (485) | 56.5 (725) | 84.7 (1090) | 140.9 (1820) | 235.0 (3030) |
| 538 (1000) | 1.4 (20) | 25.2 (365) | 33.4 (485) | 50.0 (725) | 75.2 (1090) | 125.5 (1820) | 208.9 (3030) |
Industrial Applications of Incoloy 825 Flanges
Dual oxidising-reducing acid resistance and chloride SCC immunity drive Alloy 825 flange selection across 6 industries:
- Phosphoric acid plant piping flanges, evaporator connections, and scrubber manifolds. 825 is the industry-standard flange material for wet-process H₃PO₄ production.
- Acid piping manifold flanges, pickling tank connections, and acid regeneration plant piping.
- Sour gas gathering system flanges, H₂S-bearing pipeline connections. Meets NACE MR0175 / ISO 15156 requirements for sulfide stress cracking resistance.
- Seawater-cooled heat exchanger flanges, desalination plant piping.
- FGD scrubber ducting flanges, waste acid neutralisation piping, effluent treatment systems handling mixed acid condensates.
- Nuclear fuel reprocessing piping flanges require nitric acid resistance and radiation tolerance for long-term service.
How to Order Incoloy 825 Flanges from Nicorex Alloys
Provide these following details to place an order for Incoloy 825 flanges:
- Flange Type — WNRF / BLRF / SORF / SWRF / RTJ
- Size — NPS and Schedule (½" to 24"+)
- Pressure Class — 150 / 300 / 600 / 900 / 1500 / 2500
- Face Type — RF / FF / RTJ / T&G
- Material Grade — Incoloy 825 / UNS N08825 / W.Nr. 2.4858
- Quantity — Number of pieces or kg
- Standard — ASME B16.5 / B16.47 / ASTM B564
- Additional Requirements — NACE, PMI, IGC, stabilising anneal
- Documentation — MTC 3.1/3.2, PMI, IGC Report, TPI Certificate
- Delivery — Domestic / International (specify destination)
Custom sizes available. Quotation within 24 hours.
Frequently Asked Questions
What makes 825 better than 316L for acid piping flanges?
Incoloy 825 has 42% Ni (vs 10% in 316L), providing immunity to chloride SCC. It resists sulfuric, phosphoric, and nitric acids at concentrations and temperatures where 316L corrodes rapidly. Ti stabilisation prevents sensitisation in welded flanges.
Is Incoloy 825 the same as Inconel 825?
The alloy (UNS N08825) is sometimes called both. Incoloy is the correct trade name from Special Metals. Incoloy refers to nickel-iron-chromium alloys; Inconel refers to nickel-chromium alloys. Technically, 825 is an Incoloy grade.
Can 825 flanges handle hydrofluoric acid (HF)?
Incoloy 825 has moderate resistance to dilute HF. For concentrated HF, Monel 400 flanges are preferred due to superior fluoride resistance.
Does 825 meet NACE MR0175 for sour gas?
Yes. Solution-annealed Incoloy 825 meets NACE MR0175 / ISO 15156 for sour environments with specific H₂S partial pressure limits.
What filler metal for welding 825 fanges?
ERNiCrMo-3 (Inconel 625 filler, AWS A5.14) is commonly used. For matching chemistry, ERNiFeCr-1 may be specified. No PWHT required; Ti stabilisation protects against sensitisation.