A194 Grade 8 Heavy Hex Nuts
304 stainless heavy hex nut for A193 and A320 B8 studs — solution treated, 80 ksi proof load, corrosion resistant from cryogenic to 1500 °F.
Robust fastener with a thicker, wider hexagonal shape for high-stress applications. Manufactured and stocked across ASTM A194 grades from 2H to 8MA, plain or coated.
ASTM A194 Grade 8 is the 304 stainless steel nut that pairs with A193 and A320 Grade B8 studs. It is forged or machined from solution-annealed bar for maximum corrosion resistance and ductility, with an 80 ksi proof load and a hardness range of 126 to 300 HBW.
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What A194 Grade 8 must meet.
| Nut style and size (in.) | Proof load stress (ksi) | Hardness, min | Hardness, max |
|---|---|---|---|
| Heavy hex, all sizes | 80 | 126 HBW / 60 HRB | 300 HBW / 32 HRC |
| Hex (finished pattern), all sizes | 75 | 126 HBW / 60 HRB | 300 HBW / 32 HRC |
| Grade 8A (solution treated in the finished condition), all sizes | 80 heavy hex · 75 hex | 126 HBW / 60 HRB | 192 HBW / 90 HRB |
Values per ASTM A194/A194M-24, Tables 1, 2 and 3 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Jam nuts: 46 % of the tabulated proof load. Strain-hardened Grade 8 nuts (S1) are proof tested to 125 / 115 / 105 / 100 ksi heavy hex by size and hardness limits do not apply.
Grade 8 nuts are hot or cold forged, or machined from hot-forged, hot-rolled or cold-drawn bar, with no heat-treatment requirement (A194 clause 6.6). The 8A type is carbide solution treated after forging or machining (clause 6.7), which lowers hardness to the 126–192 HBW / 60–90 HRB window.
Full A194 8 data sheet: chemistry, physical properties and standards →
Made to standard or to your drawing.
- Waterworks and water treatment flanges
- Food, beverage and pharmaceutical equipment
- Cryogenic and LNG piping
- Architectural and marine-atmosphere hardware
- Chemical process piping in mild media