Inconel 825 / Incoloy 825 FlangesASTM B564 UNS N08825 · Manufacturer, stockist & exporter, India
Also sold as Incoloy 825 · Alloy 825 · UNS N08825 · W.Nr 2.4858
Inconel 825 flanges are forged to ASTM B564 and machined to ASME B16.5 (½"–24", Class 150–2500) or ASME B16.47 for larger sizes. It is a nickel–iron–chromium alloy with molybdenum, copper and titanium, chosen for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on every heat
- NACE MR0175 on request
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is Inconel 825 Flanges?
Inconel 825 flanges is a nickel–iron–chromium alloy with molybdenum, copper and titanium supplied as flanges to ASTM B564 (UNS N08825). Buyers specify it for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas. It is also sold as Incoloy 825, Alloy 825, UNS N08825.
- What it is
- Nickel–iron–chromium alloy with molybdenum, copper and titanium
- Material
- ASTM B564
- Dimensions
- ASME B16.5 · B16.47 · EN 1092-1
- Classes
- 150 · 300 · 600 · 900 · 1500 · 2500
- Facing
- RF · FF · RTJ
- Best at
- Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas
Inconel 825 Flanges Specification & Sizes
| Material standard | ASTM B564 |
|---|---|
| Dimensional standards | ASME B16.5 (½"–24") · B16.47 Series A / B (26"–60") · B16.36 orifice · B16.48 line blanks · EN 1092-1 |
| Pressure classes | Class 150, 300, 400, 600, 900, 1500, 2500 · PN 6 – PN 100 |
| Facing | Raised face (RF) · flat face (FF) · ring type joint (RTJ) · tongue & groove |
| Bore | To match the pipe schedule — specify it on the order |
| Types | Weld neck flange · Slip-on flange · Blind flange · Socket weld flange · Threaded flange · Lap joint flange · Long weld neck flange · Orifice flange · Spectacle blind · Reducing flange · Ring type joint flange · Expander flange · Anchor flange · Swivel ring flange |
| Testing | PMI · dimensional · UT of forgings · IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
Standards on this page
Inconel 825 Flange Pressure–Temperature Rating
The class is not a pressure: the allowable pressure for 825 flanges comes from the ASME B16.5 table for its material group, and falls as temperature rises (how ratings work). ASTM B564 is in material group 3.8. B16.5 does not permit N08825 above 538 °C.
Take the actual pressures from the B16.5 rating table for group 3.8. A class is not a project pressure rating — your piping class sheet and design conditions govern.
Bolting & Gaskets for 825 Flanges
For Inconel 825 flanges the usual bolting is B7 (coated), B8M or nickel-alloy studs such as Inconel 825 from ASTM B425, as the project specifies — see Inconel 825 fasteners. Spiral-wound gaskets for this service usually use a winding in the same or a higher alloy, so the gasket does not corrode first. Facing and gasket options are compared in the flange guide.
Where Inconel 825 Flanges Are Used
Inconel 825 Flanges Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 38.0 – 46.0 |
| Iron | 22.0 min |
| Chromium | 19.5 – 23.5 |
| Molybdenum | 2.5 – 3.5 |
| Copper | 1.5 – 3.0 |
| Titanium | 0.6 – 1.2 |
| Carbon | 0.05 max |
| Manganese | 1.0 max |
| Silicon | 0.5 max |
| Aluminium | 0.2 max |
| Sulphur | 0.03 max |
Inconel 825 Flanges Mechanical Properties
| Annealed | Value |
|---|---|
| Tensile strength | 586 MPa · 85 ksi |
| Yield strength 0.2% | 241 MPa · 35 ksi |
| Elongation | 30% |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8.14 g/cm³ |
| Melting range | 1370 – 1400 °C |
| Magnetic | Non-magnetic (annealed) |
| PREN (approx.) | ≈ 31 |
Inconel 825 Equivalent Grades
Values follow ASTM B424 / B423 / B564 for UNS N08825. Always check against the edition named on your purchase order.
Inconel 825 flange dimensions — ASME B16.5 Class 150 & 300
Outside dimensions depend only on size and class, not on the alloy, so 825 flanges bolt to any B16.5 flange of the same size and class. Values in mm; thickness excludes the 1.6 mm raised face.
| NPS | Cl 150 OD | Cl 150 thickness | Cl 150 bolt circle | Cl 150 bolts | Cl 300 OD | Cl 300 thickness | Cl 300 bolt circle | Cl 300 bolts |
|---|---|---|---|---|---|---|---|---|
| ½" | 90 | 9.6 | 60.3 | 4 × ½" | 95 | 12.7 | 66.7 | 4 × ½" |
| 1" | 110 | 12.7 | 79.4 | 4 × ½" | 125 | 15.9 | 88.9 | 4 × ⅝" |
| 1½" | 125 | 15.9 | 98.4 | 4 × ½" | 155 | 19.1 | 114.3 | 4 × ¾" |
| 2" | 150 | 17.5 | 120.7 | 4 × ⅝" | 165 | 20.7 | 127.0 | 8 × ⅝" |
| 3" | 190 | 22.3 | 152.4 | 4 × ⅝" | 210 | 27.0 | 168.3 | 8 × ¾" |
| 4" | 230 | 22.3 | 190.5 | 8 × ⅝" | 255 | 30.2 | 200.0 | 8 × ¾" |
| 6" | 280 | 23.9 | 241.3 | 8 × ¾" | 320 | 35.0 | 269.9 | 12 × ¾" |
| 8" | 345 | 27.0 | 298.5 | 8 × ¾" | 380 | 39.7 | 330.2 | 12 × ⅞" |
| 10" | 405 | 28.6 | 362.0 | 12 × ⅞" | 445 | 46.1 | 387.4 | 16 × 1" |
| 12" | 485 | 30.2 | 431.8 | 12 × ⅞" | 520 | 49.3 | 450.8 | 16 × 1⅛" |
Full chart: ASME B16.5 flange dimensions.
Six-digit Harmonized System heading (nickel alloy, chapter 75). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify Inconel 825 Flanges with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. Inconel 825 is most often mixed up with SS 904L — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen; those come from the mill certificate or optical emission (OES) testing. We PMI-test nickel alloys as standard and any grade on request.
| Element | Inconel 825 | SS 904L |
|---|---|---|
| Nickel | 38.0 – 46.0 | 23.0 – 28.0 |
| Chromium | 19.5 – 23.5 | 19.0 – 23.0 |
| Molybdenum | 2.5 – 3.5 | 4.0 – 5.0 |
| Copper | 1.5 – 3.0 | 1.0 – 2.0 |
| Titanium | 0.6 – 1.2 | residual |
| Iron | 22.0 min | Balance |
| Manganese | 1.0 max | 2.00 max |
Inconel 825 Flanges Price — What Decides It
Two quotes for "825 flanges" can differ by 20% and both be fair. We quote 825 flanges per kg for full sizes and per piece for cut sizes. These six things move the price per kg, so you can compare offers like for like.
Inconel 825 flanges by type
Inconel 825 Flanges Applications
Inconel 825 is specified when the cheaper grade will not survive the service but a higher alloy would be more than the job needs. These are the jobs our buyers use it for.
Inconel 825 Flanges vs 316L, 904L and 625
| Grade | Flanges standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 316 / 316L | ASTM A182 F316L | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| Inconel 825 | ASTM B564 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L | ASTM A182 F904L | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| Inconel 625 | ASTM B564 | ≈ 51 | Seawater, high strength and high temperature in one alloy |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
Inconel 825 Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 825 fits.
Around 40% nickel takes the alloy well clear of the range where austenitic stainless steels crack in hot chlorides.
Molybdenum and copper give 825 its standing in sulphuric and phosphoric acid service, and help against pitting.
About 21% chromium handles nitric acid, nitrates and oxidising salts.
Titanium stabilises the alloy, so welded parts resist sensitisation in the heat-affected zone.
How your 825 flanges order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked and material is PMI-tested before processing.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Standards on this page
Welding & Fabricating Inconel 825 Flanges
Inconel 825 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ERNiFeCr-1 (AWS A5.14) |
|---|---|
| Over-alloyed filler | ERNiCrMo-3 wire · ENiCrMo-3 electrode |
| Preheat | Not required; keep interpass temperature low |
| Cutting | Thermal or abrasive cutting; grind off heat-tinted edges before welding |
Follow your approved WPS; this is general guidance. See also 825 fittings and 825 flanges for the matching pipe-system parts.
How to Order Inconel 825 Flanges: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Flange type and dimensional standard (B16.5 / B16.47 / EN 1092-1)
- Size, pressure class and facing
- Bore / schedule for weld neck and socket weld flanges
- Material standard and grade marking
- Certificate type and extra tests
- Delivery port, Incoterm and required date
Inconel 825 flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiInconel 825 flanges — questions buyers ask
Is Inconel 825 the same as Incoloy 825?
Yes. Incoloy 825, Alloy 825, UNS N08825 all refer to the same material, and flanges is ordered to ASTM B564 whichever name is on the enquiry.
Which standard covers Inconel 825 flanges?
ASTM B564 is the material specification for the forging; dimensions follow ASME B16.5 for ½"–24" and ASME B16.47 for 26" and above. European projects use EN 1092-1.
What pressure can a Inconel 825 Class 300 flange take?
It depends on temperature. ASTM B564 is in ASME B16.5 material group 3.8; read the Class 300 column of that group's table at your design temperature.
Which bolts should I use with Inconel 825 flanges?
Usually B7 (coated), B8M or nickel-alloy studs such as Inconel 825 from ASTM B425, as the project specifies. In corrosive or sour service the bolting material is set by the project specification.
Can a Inconel 825 flange be welded to a different pipe material?
Yes — a nickel-base filler such as ERNiCr-3 (or ERNiCrMo-3) is used when joining it to carbon steel. Weld neck bores must match the mating pipe schedule.
Can you supply Inconel 825 flanges to NACE MR0175?
Yes. Inconel 825 is listed in NACE MR0175 / ISO 15156-3 for sour service within that standard's environmental limits. State NACE compliance on the order and it is confirmed on the certificate.
Inconel 825 or Inconel 625 — which should I choose?
Inconel 825 is chosen for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas. Inconel 625 is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026