Incoloy 800 / 800H / 800HT Heavy Hex NutASTM B408 · ASME B18.2.2 · Manufacturer, stockist & exporter, India
Alloy 800 · UNS N08800 / N08810 / N08811
An Incoloy 800 / 800H / 800HT heavy hex nut is a thicker and wider hexagon nut for pressure bolting, made from Incoloy 800 / 800H / 800HT to ASTM B408. Heavy hex nuts go with stud bolts on flanges. They spread load better and resist thread stripping at high preload. Made to ASME B18.2.2.
- ASTM B408
- ASME B18.2.2
- 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 Heavy Hex Nut?
- What it is
- A thicker and wider hexagon nut for pressure bolting
- Material
- ASTM B408
- Dimensions
- ASME B18.2.2
- Grade
- Incoloy 800 / 800H / 800HT · UNS N08800
- Best at
- Furnaces, petrochemical heaters and high-temperature piping
Incoloy 800 / 800H / 800HT Heavy Hex Nut Specification
| Product | Incoloy 800 / 800H / 800HT Heavy Hex Nut |
|---|---|
| Material standard | ASTM B408 |
| Dimensional standard | ASME B18.2.2 |
| Sizes | M10 – M64 · ½" – 4" (others on request) |
| Threads | UNC · UN-8 · metric coarse |
| Testing | PMI · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
When to Choose a Heavy Hex Nut
Heavy hex nuts go with stud bolts on flanges. They spread load better and resist thread stripping at high preload. Made to ASME B18.2.2.
- Thicker than standard hex nuts
- ASME B18.2.2
- Paired with A193 studs
More on choosing: Heavy hex nut guide.
Incoloy 800 / 800H / 800HT Heavy Hex Nut: Why 800 for heavy hex nuts
Heavy hex nuts go with stud bolts on flanges. They spread load better and resist thread stripping at high preload. Made to ASME B18.2.2. 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 fasteners match nickel-alloy flanges in corrosive or hot service. 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 such as Incoloy 800 / 800H / 800HT from ASTM B408, as the project specifies |
Incoloy 800 / 800H / 800HT Heavy Hex Nut 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 |
Incoloy 800 / 800H / 800HT Heavy Hex Nut 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% |
Full chemistry, properties and equivalents are on the Incoloy 800 / 800H / 800HT grade page.
Standards on this page
Other Incoloy 800 / 800H / 800HT fasteners
Incoloy 800 / 800H / 800HT Heavy Hex Nuts for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiIncoloy 800 / 800H / 800HT Heavy Hex Nut — questions buyers ask
Why use heavy hex nuts on flanges?
They provide more thread engagement and bearing area for the high preload flange joints need.
What nut is used with Incoloy 800 / 800H / 800HT heavy hex nuts?
A nut in the same alloy, machined from ASTM B408 bar, unless the project specifies otherwise.
Which standard covers Incoloy 800 / 800H / 800HT heavy hex nuts?
The material is ASTM B408; dimensions follow ASME B18.2.2. 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 heavy hex nut?
The alloy price, the size and dimensions, 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 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026