A194 Grade 7 Heavy Hex Nuts
The Cr-Mo heavy hex nut — same 4140 steel as a B7 stud, rated for elevated temperature and the usual match for B16 and L7.
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 7 is a quenched-and-tempered chromium-molybdenum steel heavy hex nut made from the same AISI 4140 family as A193 B7. With 24 to 35 HRC hardness and a 175 ksi proof load it matches 2H in strength, and its alloy content keeps that strength at the temperatures where carbon steel begins to soften.
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What A194 Grade 7 must meet.
| Nut style and size (in.) | Proof load stress (ksi) | Hardness, min | Hardness, max |
|---|---|---|---|
| Heavy hex, all sizes | 175 | 248 HBW / 24 HRC | 327 HBW / 35 HRC |
| Hex (finished pattern), all sizes | 150 | 248 HBW / 24 HRC | 327 HBW / 35 HRC |
Values per ASTM A194/A194M-24, Tables 1, 2 and 5 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Quenched in liquid and tempered at 1100 °F (595 °C) minimum. Grade 7L is impact tested under Supplementary Requirement S3 to the A320 L7 Charpy procedure for low-temperature service (not required below ⅝ in.).
Full A194 7 data sheet: chemistry, physical properties and standards →
Made to standard or to your drawing.
- Steam turbine and HP steam flange bolting with B16
- Low-temperature service with A320 L7 (Grade 7L)
- Hot hydrocarbon and refinery bolting
- Valve bonnets and pump casings at temperature