Structural Bolt (A325) vs. Hex Bolt (Grade 8)
Both are strong hex bolts, but a structural bolt is certified for steel-to-steel framing while a Grade 8 bolt is a general-purpose fastener.
| Feature | Structural Bolt (A325) | Hex Bolt (Grade 8) |
|---|---|---|
| Specification | ASTM A325 / F3125 | SAE J429 Grade 8 |
| Head | Heavy hex | Standard hex |
| Tensile strength | 120 ksi (A325) | 150 ksi |
| Intended use | Structural steel connections | General high-strength bolting |
| Washers | F436 hardened, required | Standard washers |
Verdict
In structural steelwork, use A325/F3125 bolts — code and the engineer of record require them. Use Grade 8 for machinery and general high-strength work.