Heavy Hex Nut (ASME B18.2.2 / ASTM A194 2H)
Heavy hex nuts have thicker bodies and larger across-flats than standard hex nuts of the same nominal size. ASTM A194 Grade 2H is the workhorse heavy hex nut for high-temperature, high-pressure flange bolting — almost always paired with A193 B7 stud bolts.
Specifications
| Standards | ASME B18.2.2 heavy series, ASTM A194 (Grades 2H, 2HM, 4, 7, 8) |
|---|---|
| Diameter Range | 1/4" – 4" |
| Common Pairing | A193 B7 studs for flange bolting |
| Surface Finish | Plain, HDG, Zinc plated |
| Documentation | Mill Test Certificate per heat lot |
Frequently Asked Questions
What does the '2H' designation mean?
A194 Grade 2H is a quenched and tempered medium-carbon steel heavy hex nut suitable for use with high-tensile bolting at moderate temperatures. The 'H' indicates a hardness range of 24-38 HRC. For higher temperatures or special service, other A194 grades (4, 7, 8M) may be specified.
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