A194 7M Heavy Hex Nuts
Controlled-hardness Cr-Mo nut for sour service at temperature — 235 HBW max, NACE MR0175, for B7M and L7M studs.
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 7M is Grade 7 tempered to a maximum of 235 HBW for hydrogen sulfide service. It keeps the chromium-molybdenum chemistry that resists softening at temperature while meeting the 22 HRC ceiling of NACE MR0175 / ISO 15156, and it is hardness tested on every piece.
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What A194 7M must meet.
| Nut style and size (in.) | Proof load stress (ksi) | Hardness, min | Hardness, max |
|---|---|---|---|
| Heavy hex, all sizes | 150 | 159 HBW / 84 HRB | 235 HBW / 99 HRB |
| Hex (finished pattern), all sizes | 135 | 159 HBW / 84 HRB | 235 HBW / 99 HRB |
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. 100 percent hardness testing; final stress relief after machining at not less than 50 °F below the original tempering temperature (1200 °F minimum in a furnace after an induction temper above 1300 °F).
Quenched in liquid and tempered at 1150 °F (620 °C) minimum. Hardness verified on every nut.
Full A194 7M data sheet: chemistry, physical properties and standards →
Made to standard or to your drawing.
- Hot sour service flange bolting
- Sour gas wellheads and process units
- Hydrotreater and sulfur recovery bolting
- Any Grade 7 application requiring NACE compliance