ASTM A193 Grade B8M Standards

Heavy Hex Bolts ASME B18.2.1

Heavy Hex Bolts ASME B18.2.1

ASME B18.2.1 Heavy Hex Bolts

Dimensions of ASME B18.2.1 Heavy Hex Bolts

Nominal Size or
Basic product Diameter		 Full Size Body Diameter, E Width Across Flats, F Width Across Corners, G Head Height, H Radius of Fillet, R Thread Length for
Bolt Lengths, LT
6 in. and Shorter Over 6 in.
Max Min Basic Max Min Max Min Basic Max Min Max Min Nom Nom
3/8 0.3750 0.388 0.360 11/6 0.688 0.669 0.794 0.763 1/4 0.268 0.226 0.03 0.01 1.000 1.250
1/2 0.5000 0.515 0.482 7/8 0.875 0.850 1.010 0.969 11/32 0.364 0.302 0.03 0.01 1.250 1.500
5/8 0.6250 0.642 0.605 11/16 1.062 1.031 1.227 1.175 27/64 0.444 0.378 0.06 0.02 1.500 1.750
3/4 0.7500 0.768 0.729 1 1/4 1.250 1.212 1.443 1.383 1/2 0.524 0.455 0.06 0.02 1.750 2.000
7/8 0.8750 0.895 0.852 1 7/16 1.438 1.394 1.660 1.589 37/64 0.604 0.531 0.06 0.02 2.000 2.250
1 1.000 1.022 0.976 1 5/8 1.625 1.575 1.876 1.796 43/64 0.700 0.591 0.09 0.03 2.250 2.500
1 1/8 1.1250 1.149 1.098 1 13/16 1.812 1.756 2.093 2.002 3/4 0.780 0.658 0.09 0.03 2.500 2.750
1 1/4 1.2500 1.277 1.223 2 2.000 1.938 2.309 2.209 27/32 0.876 0.749 0.09 0.03 2.750 3.000
1 3/8 1.3750 1.404 1.345 2 3/16 2.188 2.119 2.526 2.416 29/32 0.940 0.810 0.09 0.03 3.000 3.250
1 1/2 1.5000 1.531 1.470 2 3/8 2.375 2.300 2.742 2.622 1 1.036 0.902 0.09 0.03 3.250 3.500
1 5/8 1.6250 1.658 1.591 2 9/16 2.562 2.481 2.959 2.829 1 3/32 1.116 0.978 0.09 0.03 3.500 3.750
1 3/4 1.7500 1.785 1.716 2 3/4 2.750 2.662 3.175 3.035 1 5/32 1.196 1.054 0.12 0.04 3.750 4.000
1 7/8 1.8750 1.912 1.839 2 15/16 2.938 2.844 3.392 3.242 1 1/4 1.276 1.130 0.12 0.04 4.000 4.250
2 2.000 2.039 1.964 3 1/8 3.125 3.025 3.608 3.449 1 11/32 1.388 1.175 0.12 0.04 4.250 4.500
2 1/4 2.2500 2.305 2.214 3 1/2 3.500 3.388 4.041 3.862 1 1/2 1.548 1.327 0.19 0.06 4.750 5.000
2 1/2 2.5000 2.559 2.461 3 7/8 3.875 3.750 4.474 4.275 1 21/32 1.708 1.479 0.19 0.06 5.250 5.500
2 3/4 2.7500 2.827 2.711 4 1/4 4.250 4.112 4.907 4.688 1 13/16 1.869 1.632 0.19 0.06 5.750 6.000
3 3.000 3.081 2.961 4 5/8 4.625 4.475 5.340 5.102 2 2.060 1.815 0.19 0.06 6.250 6.500

Dimensions of Screw Threads

Nomianal Size or Basic product Diameter Threads per inch. Major Diameter Root Diameter Length Tolerance
Max. Min. Max. Min. ≥ 6 in. > 6 in.
No. 10 0.190 11 0.199 0.178 0.122 0.107 ±0.12 ±0.25
1/4 0.250 10 0.260 0.237 0.177 0.160 ±0.12 ±0.25
5/16 0.312 9 0.324 0.298 0.228 0.210 ±0.12 ±0.25
3/8 0.375 7 0.388 0.360 0.268 0.250 ±0.12 ±0.25
1/2 0.500 6 0.515 0.482 0.374 0.354 ±0.12 ±0.25
5/8 0.625 5 0.642 0.605 0.473 0.453 ±0.25 ±0.25
3/4 0.750 4 1/2 0.768 0.729 0.582 0.562 ±0.25 ±0.25
7/8 0.875 4 0.895 0.852 0.686 0.665 ±0.25 ±0.25
1 1.000 3 1/2 1.022 0.976 0.784 0.760 ±0.25 ±0.25
1 1/8 1.125 3 1/4 1.149 1.100 0.892 0.867 ±0.25 ±0.25
1 1/4 1.250 3 1/4 1.277 1.223 1.017 0.987 ±0.25 ±0.25