Hardware

Recommended Nuts and Washers

black-nut-and-washerThe recommended grade of nut for an ASTM A325 structural bolt is ASTM A563 Grade D, DH, or C. ASTM A194 2H is also an acceptable substitute. These ASTM grades are all high strength and go through a heat treating process required to develop their mechanical characteristics. The reasoning behind one grade being preferred over another normally has to do with availability. There are certain sizes that may be harder to find in the market place in a given grade, needing to be specially fabricated, in which case a grade substitution would be desired. There may also be situations where the project must follow guidelines requiring that the hardware be melted and manufactured in certain geographical areas. Being that A325 type 3 bolts are made from weathering steel, the grade of nut used would be ASTM A563 Grade DH3 or C3. As far as the washers are concerned, the recommended grade is the ASTM F436 hardened washer, type 1 or 3 depending on the type of bolt grade.

A325 Recommended Hardware

Nuts Washers
Type 1 Type 3 Type 1 Type 3
Plain Galvanized Plain
A563C, C3, D, DH, DH3 A563DH A563C3, DH3 F436-1 F436-3
Note: Nuts conforming to A194 Grade 2H are a suitable substitute for use with A325 heavy hex structural bolts. The ASTM A563 Nut Compatibility Chart has a complete list of specifications.

Heavy Hex Nut Dimensions

Click table to show drawing
Bolt Diam. F C H Weight
(lbs.)
Width Across Flats Width Across Corners Thickness
Basic Max Min Max Min Basic Max Min
1⁄2 7⁄8 0.875 0.850 1.010 0.969 31⁄64 0.504 0.464 0.07
5⁄8 11⁄16 1.062 1.031 1.227 1.175 39⁄64 0.631 0.587 0.12
3⁄4 11⁄4 1.250 1.212 1.443 1.382 47⁄64 0.758 0.710 0.20
7⁄8 17⁄16 1.438 1.394 1.660 1.589 55⁄64 0.885 0.833 0.30
1 15⁄8 1.625 1.575 1.876 1.796 63⁄64 1.012 0.956 0.43
11⁄8 113⁄16 1.812 1.756 2.093 2.002 17⁄64 1.139 1.079 0.59
11⁄4 2 2.000 1.938 2.309 2.209 17⁄32 1.251 1.187 0.79
13⁄8 23⁄16 2.188 2.119 2.526 2.416 111⁄32 1.378 1.310 1.02
11⁄2 23⁄8 2.375 2.300 2.742 2.622 115⁄32 1.505 1.433 1.31

Hardened Washer Dimensions

Click table to show drawing
Bolt Size B A C Weight (lbs.) Per 1000 Pieces Part Numbers
Outside Diameter Inside Diameter Thickness Domestic
Min Max Black Galvanized
1⁄2 11⁄16 17⁄32 0.097 0.177 18 16440 16441
5⁄8 15⁄16 11⁄16 0.122 0.177 33 16442 16443
3⁄4 115⁄32 13⁄16 0.122 0.177 41 16444 16445
7⁄8 13⁄4 15⁄16 0.136 0.177 64 16446 16447
1 2 11⁄16 0.136 0.177 82 16448 16449
11⁄8 21⁄4 13⁄16 0.136 0.177 105 16450 16451
11⁄4 21⁄2 13⁄8 0.136 0.177 133 16452 16453
13⁄8 23⁄4 11⁄2 0.136 0.177 163 16454 16455
11⁄2 3 15⁄8 0.136 0.177 200 16456 16457

Load Indicating Washers (DTI)

dti-squirterLoad indicating washers (LIW) or direct tension indicating washers (DTI) are used to develop the correct tension when installing ASTM A325 structural bolts. Standard DTIs and Squirter™ DTIs are manufactured to ASTM F959. They are available as domestically manufactured in the USA and in either plain finish steel or mechanically galvanized. The sizes that they are available coincide with the A325 specification, 1/2″ diameter through 1-1/2″.

Load Indicating Washer Dimensions

Click table to show drawing
Bolt Size B C A Number of Protrusions PTD* Max Part Numbers
Max OD Thickness After Compression ID Max Squirter Standard
Black Galvanized Black Galvanized
1⁄2 1.187 0.120 0.527 4 0.788 12621 12622 16485 17287
5⁄8 1.375 0.140 0.658 4 0.956 12623 12624 15909 17288
3⁄4 1.625 0.140 0.790 5 1.125 12625 12626 12678 17289
7⁄8 1.875 0.160 0.921 5 1.294 12627 12628 12645 17290
1 2.000 0.180 1.052 6 1.463 12629 12630 12646 17291
11⁄8 2.250 0.180 1.183 6 1.631 - - 18996 18997
11⁄4 2.500 0.180 1.315 7 1.800 - - 18371 17293
13⁄8 2.750 0.180 1.446 7 1.969 - - 17294 19419
11⁄2 3.000 0.180 1.577 8 2.138 18408 - - 19418