Dimensions

structuralASTM A325 structural bolts are designed for steel to steel connections. Because they are used in such a specific application, they have dimensional characteristics that are unique and limited compared to most other fastener grades. This includes stock sizes available in the market place, length tolerances, short thread lengths, and the actual head dimensions are the same as any heavy hex head bolt (Dimensions per ASME B18.2.6 2011).

Available Sizes

Although technically any size A325 can be custom manufactured, there are certain restrictions as well as common lengths which are more readily available in the marketplace. Depending on the diameter, there may be longer lengths available.

Diameters Allowed: 1/2″ – 1-1/2″
Available Lengths: Up to 6″ – 10″ maximum (depending on diameter)
Available  Finish: Plain Finish or Hot Dip Galvanized
Origin: Import or Domestic

Bolt Length Tolerances

Nominal Length, in. Nominal Size, in.
1⁄2 5⁄8 3⁄4 thru 1 11⁄8 thru 11⁄2
Thru 6 in. -0.12 -0.12 -0.19 -0.25
Over 6 in. -0.19 -0.25 -0.25 -0.25

Structural Bolt Dimensions

Although the head dimensions for structural bolts are the same as any heavy hex headed fastener per ASME B18.2.6 2011, A325 heavy hex bolts have a shorter thread length than most other construction fastener grades.

Click table to show drawing
Bolt Diameter D F C H T
Body Diameter Width Across Flats Width Across Corners Height Thread Length
Max Basic Max Min Max Min Basic Max Min Basic
1⁄2 0.515 7⁄8 0.875 0.850 1.010 0.969 5⁄16 0.323 0.302 1.00
5⁄8 0.642 11⁄16 1.062 1.031 1.227 1.175 25⁄64 0.403 0.378 1.25
3⁄4 0.768 11⁄4 1.250 1.212 1.443 1.383 15⁄32 0.483 0.455 1.38
7⁄8 0.895 17⁄16 1.438 1.394 1.660 1.589 35⁄64 0.563 0.531 1.50
1 1.022 15⁄8 1.625 1.575 1.876 1.796 39⁄64 0.627 0.591 1.75
11⁄8 1.149 113⁄16 1.812 1.756 2.093 2.002 11⁄16 0.718 0.658 2.00
11⁄4 1.277 2 2.00 1.938 2.309 2.209 25⁄32 0.813 0.749 2.00
13⁄8 1.404 23⁄16 2.188 2.119 2.526 2.416 27⁄32 0.878 0.810 2.25
11⁄2 1.531 23⁄8 2.375 2.300 2.742 2.622 15⁄16 0.974 0.902 2.25

Dimensions per ASME B18.2.6 2011