Incoloy 800 / 800H / 800HT Lap Joint FlangeASTM B564 · ASME B16.5 · Manufacturer, trader & exporter, India
Alloy 800 · UNS N08800 / N08810 / N08811 · LJ
An Incoloy 800 / 800H / 800HT lap joint flange is a loose flange that sits behind a stub end welded to the pipe, made from Incoloy 800 / 800H / 800HT to ASTM B564. A lap joint flange rotates freely, making bolt alignment easy on lines that are dismantled often. In corrosive service the flange never touches the fluid, so it can be carbon steel while the stub end is the alloy — a big saving.
- 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 Lap Joint Flange?
- What it is
- A loose flange that sits behind a stub end welded to the pipe
- Material
- ASTM B564
- Dimensions
- ASME B16.5
- Grade
- Incoloy 800 / 800H / 800HT · UNS N08800
- Best at
- Furnaces, petrochemical heaters and high-temperature piping
Incoloy 800 / 800H / 800HT Lap Joint Flange Specification
| Product | Incoloy 800 / 800H / 800HT Lap Joint Flange |
|---|---|
| Material standard | ASTM B564 |
| Dimensional standard | ASME B16.5 |
| 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 Lap Joint Flange
A lap joint flange rotates freely, making bolt alignment easy on lines that are dismantled often. In corrosive service the flange never touches the fluid, so it can be carbon steel while the stub end is the alloy — a big saving.
- Used with a stub end (MSS SP-43 or ASME B16.9)
- Flange can be a cheaper material than the stub end
- Lower pressure rating than a weld neck
More on choosing: Lap joint flange guide.
Incoloy 800 / 800H / 800HT Lap Joint Flange: Why 800 for lap joint flanges
A lap joint flange rotates freely, making bolt alignment easy on lines that are dismantled often. In corrosive service the flange never touches the fluid, so it can be carbon steel while the stub end is the alloy — a big saving. 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 Lap Joint 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 Lap Joint 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 Lap Joint 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 Lap Joint Flange — questions buyers ask
Does a lap joint flange have to be the same alloy as the pipe?
No. Only the stub end touches the fluid, so the backing flange is often carbon steel, saving the cost of an alloy forging.
Can Incoloy 800 / 800H / 800HT lap joint 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 lap joint flanges?
The material is ASTM B564; dimensions follow ASME B16.5. 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 lap joint 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