Incoloy 800 / 800H / 800HT Weld Neck FlangeASTM B564 · ASME B16.5 · Manufacturer, trader & exporter, India
Alloy 800 · UNS N08800 / N08810 / N08811 · WNRF
An Incoloy 800 / 800H / 800HT weld neck flange is a flange with a long tapered hub that is butt-welded to the pipe, made from Incoloy 800 / 800H / 800HT to ASTM B564. Choose a weld neck flange for high pressure, high or low temperature and cyclic loading. The tapered hub moves stress away from the flange face, and the full-penetration butt weld can be radiographed.
- ASTM B564
- ASME B16.5
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an Incoloy 800 / 800H / 800HT Weld Neck Flange?
- What it is
- A flange with a long tapered hub that is butt-welded to the pipe
- Material
- ASTM B564
- Dimensions
- ASME B16.5 · B16.47
- Grade
- Incoloy 800 / 800H / 800HT · UNS N08800
- Best at
- Furnaces, petrochemical heaters and high-temperature piping
Incoloy 800 / 800H / 800HT Weld Neck Flange Specification
| Product | Incoloy 800 / 800H / 800HT Weld Neck Flange |
|---|---|
| Material standard | ASTM B564 |
| Dimensional standard | ASME B16.5 · B16.47 |
| Sizes | ½" – 24" (ASME B16.5) · 26" – 60" (ASME B16.47) |
| Pressure class | Class 150, 300, 400, 600, 900, 1500, 2500 · PN 6 – PN 100 |
| Facing | RF · FF · RTJ · tongue & groove |
| Bore | To match pipe schedule (state on order) |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose a Weld Neck Flange
Choose a weld neck flange for high pressure, high or low temperature and cyclic loading. The tapered hub moves stress away from the flange face, and the full-penetration butt weld can be radiographed.
- Bore must match the pipe schedule — state it on the order
- Hub length and taper per ASME B16.5 / B16.47 tables
- Most common facing: raised face; RTJ for high-pressure classes
More on choosing: Weld neck flange guide.
Incoloy 800 / 800H / 800HT Weld Neck Flange: Why 800 for weld neck flanges
Choose a weld neck flange for high pressure, high or low temperature and cyclic loading. The tapered hub moves stress away from the flange face, and the full-penetration butt weld can be radiographed. In Incoloy 800 / 800H / 800HT, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Nickel-alloy flanges are used where acids, chlorides or heat defeat stainless. Incoloy 800 / 800H / 800HT is picked for furnaces, petrochemical heaters and high-temperature piping. |
|---|---|
| Typical service | Petrochemical — Steam-methane reformer and ethylene furnace piping. |
| Bolting | B7 (coated), B8M or nickel-alloy studs in Incoloy 800 / 800H / 800HT (bar to ASTM B408, where applicable), as the project specifies |
| Welding to carbon steel | A nickel-base filler such as ERNiCr-3 (or ERNiCrMo-3) is used when joining it to carbon steel |
| Matching filler | ERNiCr-3 (AWS A5.14) |
Incoloy 800 / 800H / 800HT Weld Neck Flange Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Nickel | As specified |
| Chromium | As specified |
| Iron | As specified |
| Carbon | As specified |
| Aluminium | As specified |
| Titanium | As specified |
| Copper | As specified |
| Manganese | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM B409 for UNS N08800 / N08810.
Incoloy 800 / 800H / 800HT Weld Neck Flange Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM B409 for UNS N08800 / N08810 — Annealed plate.
Full chemistry, properties and equivalents are on the Incoloy 800 / 800H / 800HT grade page.
Other Incoloy 800 / 800H / 800HT flanges
Incoloy 800 / 800H / 800HT Weld Neck Flange dimensions — ASME B16.5 Class 150 & 300
Outside diameter, thickness and bolting are set by 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.
Incoloy 800 / 800H / 800HT Weld Neck Flange — questions buyers ask
Why is the bore important on a weld neck flange?
The flange bore is machined to the inside diameter of the pipe schedule, so the weld is smooth inside. A wrong bore leaves a step that disturbs flow and complicates the weld.
Can Incoloy 800 / 800H / 800HT weld neck flanges be welded to carbon steel?
Yes — a nickel-base filler such as ERNiCr-3 (or ERNiCrMo-3) is used when joining it to carbon steel.
Which standard covers Incoloy 800 / 800H / 800HT weld neck flanges?
The material is ASTM B564; dimensions follow ASME B16.5 · B16.47. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a Incoloy 800 / 800H / 800HT weld neck flange?
The alloy price, the size and pressure class, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026