SS 310 / 310S Heavy Hex NutUNS S31008 · ASME B18.2.2 · Manufacturer, trader & exporter, India
AISI 310S · UNS S31008
An SS 310 / 310S heavy hex nut is a thicker and wider hexagon nut for pressure bolting. Finished fastener specification not asserted; may be machined from ASTM A276 / A479 bar (UNS S31008), where applicable; finished fastener requirements are to the purchase specification or project drawing. 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.
- UNS S31008
- 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 SS 310 / 310S Heavy Hex Nut?
- What it is
- A thicker and wider hexagon nut for pressure bolting
- Finished spec
- Not asserted
- Material / feedstock
- ASTM A276 / A479 bar (UNS S31008), where applicable
- Dimensions
- ASME B18.2.2
- Grade
- SS 310 / 310S · UNS S31008
- Best at
- Furnaces, burners and heat treatment at high temperature
SS 310 / 310S Heavy Hex Nut Specification
| Product | SS 310 / 310S Heavy Hex Nut |
|---|---|
| Finished fastener specification | Not asserted |
| Material / feedstock specification | ASTM A276 / A479 bar (UNS S31008), where applicable |
| Dimensional standard | ASME B18.2.2 |
| Manufacturing route | May be machined from bar, where applicable |
| Project / purchase specification | Yes — finished fastener requirements are to the purchase specification or project drawing |
| Sizes | M10 – M64 · ½" – 4" (others on request) |
| Threads | UNC · UN-8 · metric coarse |
| 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 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.
SS 310 / 310S Heavy Hex Nut: Why 310S 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 SS 310 / 310S, 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 | Stainless fasteners resist atmospheric and process corrosion. SS 310 / 310S is picked for furnaces, burners and heat treatment at high temperature. |
|---|---|
| Typical service | Furnace parts — Muffles, retorts, radiant tubes and conveyor belts. |
| Bolting | A193 B8 or project-specified bolting |
SS 310 / 310S Heavy Hex Nut Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S31008.
SS 310 / 310S Heavy Hex Nut Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | 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 A240 for UNS S31008 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 310 / 310S grade page.
Standards on this page
Other SS 310 / 310S fasteners
SS 310 / 310S 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 SS 310 / 310S heavy hex nuts?
Usually a nut in the same alloy — it may be machined from ASTM A276 / A479 bar, where applicable; finished requirements are to the purchase specification or project drawing.
Which standard covers SS 310 / 310S heavy hex nuts?
Finished fastener specification: Not asserted. Material / feedstock: ASTM A276 / A479 bar (UNS S31008), where applicable. Dimensions: ASME B18.2.2. State the finished specification, material and dimensions on your purchase order or project drawing.
What decides the price of a SS 310 / 310S 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 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