When A325 isn’t enough. Alloy-steel structural bolts at the top of the strength range — with one hard rule about coatings.
ASTM A490 covers high-strength alloy-steel structural bolts, ½″ to 1½″ — used where A325 would take too many bolts. Now published as ASTM F3125 Grade A490. Minimum 150 ksi tensile, and a critical handling rule: A490 is never hot-dip galvanized.
High-strength structural, ½–1½″
“A490” stamped on the head
Heavy structural steel connections
| Size | Proof | Yield | Tensile (min) |
|---|---|---|---|
| ½–1½″ | 120 | 130 | 150 |
A490 carries the heaviest structural loads — large connections and high-demand joints where the higher strength means fewer bolts. Same family of work as A325, one strength tier up. It runs with the same heavy DH / 2H nuts and F436 washers.
Never hot-dip galvanize A490. The high-strength alloy is prone to hydrogen embrittlement, so zinc galvanizing is prohibited. For corrosion resistance, use weathering-steel (Type 3) A490 or an approved coating — not galvanizing.
The head is stamped “A490” with the maker’s mark, on a heavy hex head. If you see “A490” and a zinc-galvanized finish, stop — that combination shouldn’t exist. Ask us.
A490 structural bolts with matching nuts and washers — and we’ll steer the finish correctly. Give us the size and quantity.
