Incoloy 800 / 800H / 800HT FastenersASTM B408 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 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM B408 bar stock to ASME B18 dimensions. 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 Fasteners?
Incoloy 800 / 800H / 800HT fasteners is a nickel–iron–chromium alloy for high-temperature service supplied as fasteners to ASTM B408 (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
- Bar stock
- ASTM B408
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- Furnaces, petrochemical heaters and high-temperature piping
Incoloy 800 / 800H / 800HT Fasteners Specification & Sizes
| Material | ASTM B408 |
|---|---|
| Dimensional standards | ASME B18.2.1 (bolts) · B18.2.2 (nuts) · B18.31.2 (studs) · DIN 931 / 933 / 934 |
| Types | Stud bolt · Hex bolt · Heavy hex nut · Hex nut · Washer · Threaded rod · U-bolt · Eye bolt · Anchor bolt · Foundation bolt · Socket head cap screw · Machine screw |
| Threads | UNC, UN-8 and metric coarse |
| Coating | Plain · PTFE on request |
| Documents | EN 10204 3.1 |
Incoloy 800 / 800H / 800HT Stud Bolts: Grade & Nut Pairing
Incoloy 800 / 800H / 800HT studs and nuts are machined from ASTM B408 bar; the nut is usually the same alloy.
Torque (T = K × F × d), stud length and coatings are covered in the fasteners guide.
| Galling | Stainless and nickel-alloy threads gall — always use anti-seize, and avoid high-speed tightening |
|---|---|
| Coatings | Usually supplied plain; PTFE coating on request to ease tightening |
| Marking | Grade symbol and maker's mark on each stud end and nut, as the standard requires |
| Certificates | EN 10204 3.1 for the bar heat; mechanical test reports on the finished bolts on request |
Incoloy 800 / 800H / 800HT Fasteners 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 Fasteners 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.
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 Fasteners 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 fasteners by type
Incoloy 800 / 800H / 800HT Fasteners 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 Fasteners vs 310S, 600 and 825
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Inconel 600 | ASTM B166 | — | High-temperature oxidation, caustic and nuclear service |
| Incoloy 800 / 800H / 800HT | ASTM B408 | — | Furnaces, petrochemical heaters and high-temperature piping |
| SS 310 / 310S | ASTM A276 / A479 | ≈ 25 | Furnaces, burners and heat treatment at high temperature |
| Inconel 825 | ASTM B425 | ≈ 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 fasteners 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 Fasteners
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 Fasteners: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Fastener type, size and length
- Thread form
- Material and marking
- Quantity in sets
- Certificate type
- Delivery port and date
Incoloy 800 / 800H / 800HT fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiIncoloy 800 / 800H / 800HT fasteners — 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 fasteners is ordered to ASTM B408 whichever name is on the enquiry.
Why use Incoloy 800 / 800H / 800HT bolts instead of B7 carbon steel?
On Incoloy 800 / 800H / 800HT flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with Incoloy 800 / 800H / 800HT stud bolts?
A heavy hex nut machined from the same Incoloy 800 / 800H / 800HT bar (ASTM B408), unless the project specifies otherwise.
How do I stop Incoloy 800 / 800H / 800HT bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
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