Incoloy 800 / 800H / 800HT FlangesASTM B564 UNS N08800 · Manufacturer, stockist & exporter, India
Also sold as Alloy 800 · UNS N08800 / N08810 / N08811 · W.Nr 1.4876 · Incoloy 800H
Incoloy 800 / 800H / 800HT 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 for high-temperature service, chosen for furnaces, petrochemical heaters and high-temperature piping. 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
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is Incoloy 800 / 800H / 800HT Flanges?
Incoloy 800 / 800H / 800HT flanges is a nickel–iron–chromium alloy for high-temperature service supplied as flanges to ASTM B564 (UNS N08800). Buyers specify it for furnaces, petrochemical heaters and high-temperature piping. It is also sold as Alloy 800, UNS N08800 / N08810 / N08811, W.Nr 1.4876.
- What it is
- Nickel–iron–chromium alloy for high-temperature service
- 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
- Furnaces, petrochemical heaters and high-temperature piping
Incoloy 800 / 800H / 800HT 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 |
Incoloy 800 / 800H / 800HT Flange Pressure–Temperature Rating
The class is not a pressure: the allowable pressure for 800 flanges comes from the ASME B16.5 table for its material group, and falls as temperature rises (how ratings work). Check the material group for ASTM B564 in B16.5 Table 1A before choosing the class.
Take the actual pressures from the B16.5 rating table for group listed for your material; your piping class sheet governs.
Bolting & Gaskets for 800 Flanges
For Incoloy 800 / 800H / 800HT flanges the usual bolting is B7 (coated), B8M or nickel-alloy studs such as Incoloy 800 / 800H / 800HT from ASTM B408, as the project specifies — see Incoloy 800 / 800H / 800HT 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.
Incoloy 800 / 800H / 800HT Flanges Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 30.0 – 35.0 |
| Chromium | 19.0 – 23.0 |
| Iron | 39.5 min |
| Carbon | 0.10 max (800) · 0.05 – 0.10 (800H) |
| Aluminium | 0.15 – 0.60 |
| Titanium | 0.15 – 0.60 |
| Copper | 0.75 max |
| Manganese | 1.5 max |
| Silicon | 1.0 max |
Incoloy 800 / 800H / 800HT Flanges Mechanical Properties
| Annealed plate | Value |
|---|---|
| Tensile strength | 520 MPa · 75 ksi (800) · 450 MPa · 65 ksi (800H) |
| Yield strength 0.2% | 205 MPa · 30 ksi (800) · 170 MPa · 25 ksi (800H) |
| Elongation | 30% |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 7.94 g/cm³ |
| Melting range | 1357 – 1385 °C |
| Magnetic | Non-magnetic |
Incoloy 800 / 800H / 800HT Equivalent Grades
Values follow ASTM B409 for UNS N08800 / N08810. Always check against the edition named on your purchase order.
Incoloy 800 / 800H / 800HT flange dimensions — ASME B16.5 Class 150 & 300
Outside dimensions depend only on size and class, not on the alloy, so 800 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 (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify Incoloy 800 / 800H / 800HT 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. Incoloy 800 / 800H / 800HT is most often mixed up with Inconel 825 — 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 | Incoloy 800 / 800H / 800HT | Inconel 825 |
|---|---|---|
| Nickel | 30.0 – 35.0 | 38.0 – 46.0 |
| Chromium | 19.0 – 23.0 | 19.5 – 23.5 |
| Molybdenum | residual | 2.5 – 3.5 |
| Copper | 0.75 max | 1.5 – 3.0 |
| Titanium | 0.15 – 0.60 | 0.6 – 1.2 |
| Iron | 39.5 min | 22.0 min |
| Manganese | 1.5 max | 1.0 max |
Incoloy 800 / 800H / 800HT Flanges Price — What Decides It
Two quotes for "800 flanges" can differ by 20% and both be fair. We quote 800 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.
Incoloy 800 / 800H / 800HT flanges by type
Incoloy 800 / 800H / 800HT Flanges Applications
Incoloy 800 / 800H / 800HT 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.
Incoloy 800 / 800H / 800HT Flanges vs 310S, 600 and 825
| Grade | Flanges standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Inconel 600 | ASTM B564 | — | High-temperature oxidation, caustic and nuclear service |
| Incoloy 800 / 800H / 800HT | ASTM B564 | — | Furnaces, petrochemical heaters and high-temperature piping |
| SS 310 / 310S | ASTM A182 F310 | ≈ 25 | Furnaces, burners and heat treatment at high temperature |
| Inconel 825 | ASTM B564 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
Incoloy 800 / 800H / 800HT 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 800 fits.
Balanced nickel and chromium resist oxidation and carburisation in furnace atmospheres.
Controlled carbon and coarse grain give 800H/HT their creep-rupture strength above 600 °C.
Aluminium and titanium improve high-temperature strength.
For aqueous acid service choose 825 instead.
How your 800 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.
Welding & Fabricating Incoloy 800 / 800H / 800HT Flanges
Incoloy 800 / 800H / 800HT welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ERNiCr-3 (AWS A5.14) |
|---|---|
| Over-alloyed filler | ERNiCrCoMo-1 for creep-critical joints |
| 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 800 fittings and 800 flanges for the matching pipe-system parts.
How to Order Incoloy 800 / 800H / 800HT 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
Incoloy 800 / 800H / 800HT flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiIncoloy 800 / 800H / 800HT flanges — questions buyers ask
Is Incoloy 800 / 800H / 800HT the same as Alloy 800?
Yes. Alloy 800, UNS N08800 / N08810 / N08811, W.Nr 1.4876 all refer to the same material, and flanges is ordered to ASTM B564 whichever name is on the enquiry.
Which standard covers Incoloy 800 / 800H / 800HT 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 Incoloy 800 / 800H / 800HT Class 300 flange take?
It depends on temperature and the material group of ASTM B564 in ASME B16.5; read the Class 300 column of that group's rating table at your design temperature.
Which bolts should I use with Incoloy 800 / 800H / 800HT flanges?
Usually B7 (coated), B8M or nickel-alloy studs such as Incoloy 800 / 800H / 800HT from ASTM B408, as the project specifies. In corrosive or sour service the bolting material is set by the project specification.
Can a Incoloy 800 / 800H / 800HT 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.
Incoloy 800 / 800H / 800HT or Inconel 825 — which should I choose?
Incoloy 800 / 800H / 800HT is chosen for furnaces, petrochemical heaters and high-temperature piping. Inconel 825 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