Several ASTM specifications require a hex head that is larger than a standard (finished) hex head. These specifications include: A193, A320 and A307B. Although A325 and A490 bolts also require a heavy hex head, please refer to Structural Bolts for dimensional specifications, since these bolts have shorter thread lengths than standard heavy hex bolts.

Applications

Heavy hex bolts can be used for many different applications that include fastening wood, steel, and other construction materials for projects such as docks, bridges, highway structures, and buildings. Heavy hex bolts with forged heads are also commonly used as headed anchor bolts.

Manufacturing

Portland Bolt manufactures heavy hex bolts from 1/2″ diameter through 2-1/2″ diameter in most ASTM, AASHTO, and SAE specifications. Special tooling can be created to produce nonstandard head dimensions or bolt heads with your company’s name and/or logo.

Stock

Portland Bolt stocks A325 Heavy Hex Structural Bolts.

Standard Thread Lengths

Bolt lengths  6″: Thread length = (2 X diameter) + 1/4″
Bolt lengths > 6″: Thread length = (2 X diameter) + 1/2″

Heavy Hex Dimensions

Click table to show drawing
Bolt DiameterDFCH
Body DiameterWidth Across FlatsWidth Across CornersHeight
MaxBasicMaxMinMaxMinBasicMaxMin
120.515780.8750.8501.0100.96911320.3640.302
580.64211161.0621.0311.2271.17527640.4440.378
340.7681141.2501.2121.4431.383120.5240.455
780.89517161.4381.3941.6601.58937640.6040.531
11.0221581.6251.5751.8761.79643640.7000.591
1181.149113161.8121.7562.0932.002340.7800.658
1141.27722.001.9382.3092.20927320.8760.749
1381.40423162.1882.1192.5262.41629320.9400.810
1121.5312382.3752.3002.7422.62211.0360.902
1581.65829162.5622.4812.9592.82913321.1160.978
1341.7852342.7502.6623.1753.03515321.1961.054
1781.912215162.9382.8443.3923.2421141.2761.130
22.0393183.1253.0253.6083.449111321.3881.175
2142.3053123.5003.3884.0413.8621121.5481.327
2122.5593783.8753.7504.4744.275121321.7081.479

Dimensions per ASME B18.2.1