Heavy Hex Structural Bolts ASTM F3125 Grade A325 (EH-BLT-HVY)

Applications & Industries

Heavy Hex Structural Bolts are bought for a small number of well-defined jobs. These are the ones we ship them for.

Industries that specify Heavy Hex Structural Bolts

• Bridges & heavy civils Slip-critical connections with hardened washers and a specified tensioning method.
• Crane & lifting structures Bolted connections in gantries, masts and runway beams.
• Structural steelwork Beam-to-column, splice and bracing connections, tensioned and inspected on site.
• Automotive & transport Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
• Steel fabrication Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
• Energy & infrastructure Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.

Typical applications

• slip-critical connections tensioned by turn-of-nut or DTI washer
• supplied as a matched assembly with a heavy hex nut and hardened washer
• bolting structural steel members where the shear plane falls on the plain shank
• joints where the property class is stated on the drawing
• clamping two machined faces to a calculated preload
• bolting brackets, motors and gearboxes to a frame

Service conditions to specify against

Marine and coastal

Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.

High load

Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.

Torque and preload

The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.

Where to use something else

• Not an alternative to an ordinary hex bolt on a machine: the short thread and large head suit plate connections, not tapped holes.
• Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.

Need help matching Heavy Hex Structural Bolts to your application? Send the assembly, the load and the environment with your enquiry and we will specify the size, material and finish against them.