Heavy-hex structural bolts to ASTM F3125 (A325/A490) form slip-critical and bearing steel-frame connections, supplied with heavy-hex nuts and hardened washers, including twist-off tension-control variants.
Conforms to

A325/A490 heavy-hex assemblies for steel connections.
A cross-section of stocked configurations. Not exhaustive — diameters, lengths, grades, and finishes extend across the full range on request.
Representative specifications — not exhaustive · NXB-STR
Match the line to the load, the environment, and the standard it answers to.
Materials
Finishes
Standards
Typical applications
Served industries
Mating parts and adjacent lines engineers reach for alongside this one.
Six-sided structural workhorse for nut or tapped-hole joints.
M5–M48 · 1/4"–2"
Hex head with an integral flange that spreads clamp load.
M6–M20 · 1/4"–3/4"
The standard six-sided nut for threaded assemblies.
M3–M48 · #4–2"
Spreads clamp load and protects the bearing surface.
M3–M36 · #6–1-1/2"
Grade, material, finish, and standard — matched to your joint and quoted from stock. Tell us the load case and we’ll confirm the line.