ASTM F436 — Hardened Structural Washers
The washer that goes with structural bolts. Hardened so it doesn’t dish or gall when the connection is tightened.
ASTM F436 covers through-hardened steel washers for use with structural bolts — A325 and A490 (F3125). An ordinary flat washer is soft; under the clamp load of a structural bolt it can cup and let the joint relax. An F436 washer holds its shape.
Covers
Hardened flat & beveled washers, ¼–4″
Identify by
“F436” and maker’s mark stamped on the face
Typical use
Structural steel connections
Types
| Type | Steel | Hardness | Used with |
|---|---|---|---|
| Type 1 | Carbon steel | HRC 38–45 | Plain or galvanized structural bolts |
| Type 3 | Weathering steel | HRC 38–45 | Weathering (Type 3) bolts on exposed steel |
Where it goes
Structural connections often call for an F436 washer under the part being turned — the nut or the bolt head — and always where the specification requires one, such as oversized or slotted holes. On sloped flanges (S-beams and channels) a beveled F436 washer squares the bolt to the steel.
How to spot it
A real F436 washer is stamped “F436” with the manufacturer’s mark. It’s thicker than a USS flat washer and noticeably harder. An unmarked washer is not F436, whatever the box says.
We stock F436 washers
Plain and galvanized F436 washers to go with A325 and A490 bolts and their nuts — the full structural set.