The structural steel connection bolt — heavy hex, heat treated. If a steel detailer calls for “A325,” this is it.
ASTM A325 covers heat-treated structural heavy hex bolts for steel-to-steel connections, ½″ to 1½″. It’s now published under ASTM F3125 as Grade A325 — same bolt, newer umbrella standard — and you’ll still hear it called A325 everywhere.
Structural heavy hex, ½–1½″
“A325” stamped on the head
Structural steel & iron-work connections
| Size | Proof | Yield | Tensile |
|---|---|---|---|
| ½–1″ | 85 | 92 | 120 |
| >1–1½″ | 74 | 81 | 105 |
A325 is the backbone of structural steel and iron work — beam-to-column connections, base plates, bracing, moment connections, both bearing and slip-critical joints. It runs with A563 DH or A194 2H heavy hex nuts and F436 structural washers — the matched set the connection design assumes.
Unlike A490, A325 can be hot-dip galvanized (Type 1), and a Type 3 weathering-steel version exists for exposed work.
The head is stamped “A325” along with the manufacturer’s mark, on a heavy hex head — thicker and wider than a standard bolt. Pair only with the matching structural nut and washer; see the nut compatibility chart.
A325 heavy hex bolts with the matching DH / 2H nuts and F436 washers — the full connection. Give us the size and quantity.
