ASME B18.2.1 Heavy Hex Screws
Dimensions of ASME B18.2.1 Heavy Hex Screws
| Nominal Size or Basic product Diameter | Body Diameter, E | Width Across Flats, F | Width Across Corners, G | Head Height, H | Minimum Wrenching Height, J | Thread Length for Screws Lengths, LT | Transition Thread Length, Y | Maximum Total Runout of Bearing Surface FIM | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6 in. & Shorter | Over 6 in. | |||||||||||||
| Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Nom. | Nom. | |||||
| 3/8 | 0.3750 | 0.3750 | 0.360 | 0.688 | 0.669 | 0.794 | 0.763 | 0.243 | 0.226 | 0.160 | 1.000 | 1.250 | 0.312 | 0.014 |
| 1/2 | 0.5000 | 0.5000 | 0.482 | 0.875 | 0.850 | 1.010 | 0.969 | 0.323 | 0.302 | 0.215 | 1.250 | 1.500 | 0.385 | 0.016 |
| 5/8 | 0.6250 | 0.6250 | 0.605 | 1.062 | 1.031 | 1.227 | 1.175 | 0.403 | 0.378 | 0.269 | 1.500 | 1.750 | 0.455 | 0.019 |
| 3/4 | 0.7500 | 0.7500 | 0.729 | 1.250 | 1.212 | 1.443 | 1.383 | 0.483 | 0.455 | 0.324 | 1.750 | 2.000 | 0.500 | 0.022 |
| 7/8 | 0.8750 | 0.8750 | 0.852 | 1.438 | 1.394 | 1.660 | 1.589 | 0.563 | 0.531 | 0.378 | 2.000 | 2.250 | 0.556 | 0.025 |
| 1 | 1.0000 | 1.000 | 0.976 | 1.625 | 1.575 | 1.876 | 1.796 | 0.627 | 0.591 | 0.416 | 2.250 | 2.500 | 0.625 | 0.028 |
| 1 1/8 | 1.1250 | 1.1250 | 1.098 | 1.812 | 1.756 | 2.093 | 2.002 | 0.718 | 0.658 | 0.461 | 2.500 | 2.750 | 0.714 | 0.032 |
| 1 1/4 | 1.2500 | 1.2500 | 1.223 | 2.000 | 1.938 | 2.309 | 2.209 | 0.813 | 0.749 | 0.530 | 2.750 | 3.000 | 0.714 | 0.035 |
| 1 3/8 | 1.3750 | 1.3750 | 1.345 | 2.188 | 2.119 | 2.526 | 2.416 | 0.878 | 0.810 | 0.569 | 3.000 | 3.250 | 0.833 | 0.038 |
| 1 1/2 | 1.5000 | 1.5000 | 1.470 | 2.375 | 2.300 | 2.742 | 2.622 | 0.974 | 0.902 | 0.640 | 3.250 | 3.500 | 0.833 | 0.041 |
| 1 5/8 | 1.6250 | 1.6250 | 1.591 | 2.562 | 2.481 | 2.959 | 2.829 | 1.038 | 0.962 | 0.694 | 3.500 | 3.750 | 0.909 | 0.044 |
| 1 3/4 | 1.7500 | 1.7500 | 1.716 | 2.750 | 2.662 | 3.175 | 3.035 | 1.134 | 1.054 | 0.748 | 3.750 | 4.000 | 1.000 | 0.048 |
| 1 7/8 | 1.8750 | 1.8750 | 1.839 | 2.938 | 2.844 | 3.392 | 3.242 | 1.198 | 1.114 | 0.802 | 4.000 | 4.250 | 1.000 | 0.052 |
| 2 | 2.000 | 2.000 | 1.964 | 3.125 | 3.025 | 3.608 | 3.449 | 1.263 | 1.175 | 0.825 | 4.250 | 4.500 | 1.111 | 0.055 |
| 2 1/4 | 2.2500 | 2.2500 | 2.214 | 3.500 | 3.388 | 4.041 | 3.862 | 1.423 | 1.327 | 0.933 | -- | 5.000 | 1.111 | 0.061 |
| 2 1/2 | 2.5000 | 2.5000 | 2.4610 | 3.8750 | 3.750 | 4.474 | 4.275 | 1.583 | 1.479 | 1.042 | -- | 5.500 | 1.250 | 0.068 |
| 2 3/4 | 2.7500 | 2.7500 | 2.7110 | 4.2500 | 4.112 | 4.907 | 4.688 | 1.744 | 1.632 | 1.151 | -- | 6.000 | 1.250 | 0.074 |
| 3 | 3.000 | 3.000 | 2.9610 | 4.6250 | 4.475 | 5.340 | 5.102 | 1.935 | 1.815 | 1.290 | -- | 6.500 | 1.250 | 0.081 |
| 3 1/4 | 3.2500 | 3.2500 | 3.2100 | 5.0000 | 4.838 | 5.774 | 5.515 | 2.126 | 1.998 | 1.399 | -- | 7.000 | 1.250 | 0.081 |
| 3 1/2 | 3.5000 | 3.5000 | 3.4610 | 5.3750 | 5.200 | 6.207 | 5.928 | 2.256 | 2.120 | 1.484 | -- | 7.500 | 1.250 | 0.098 |
| 3 3/4 | 3.7500 | 3.7500 | 3.7109 | 5.7500 | 5.562 | 6.640 | 6.341 | 2.447 | 2.303 | 1.612 | -- | 8.000 | 1.250 | 0.105 |
| 4 | 4.0000 | 4.0000 | 3.9609 | 6.1250 | 5.925 | 7.073 | 6.755 | 2.576 | 2.424 | 1.697 | -- | 8.500 | 1.250 | 0.112 |
| 4 1/4 | 4.2500 | 4.2500 | 4.2228 | 6.5000 | 6.288 | 7.506 | 7.168 | 2.768 | 2.608 | 1.826 | -- | 9.000 | 1.250 | 0.119 |
| 4 1/2 | 4.5000 | 4.5000 | 4.4727 | 6.8750 | 6.650 | 7.939 | 7.581 | 2.896 | 2.728 | 1.910 | -- | 9.500 | 1.250 | 0.126 |
| 4 3/4 | 4.7500 | 4.7500 | 4.7227 | 7.2500 | 7.012 | 8.372 | 7.994 | 3.088 | 2.912 | 2.038 | -- | 10.000 | 1.250 | 0.133 |
| 5 | 5.0000 | 5.000 | 4.9726 | 7.6250 | 7.375 | 8.805 | 8.408 | 3.217 | 3.033 | 2.123 | -- | 10.500 | 1.250 | 0.14 |
| 5 1/4 | 5.2500 | 5.2500 | 5.2226 | 8.0000 | 7.738 | 9.238 | 8.821 | 3.408 | 3.216 | 2.251 | -- | 11.000 | 1.250 | 0.147 |
| 5 1/2 | 5.5000 | 5.5000 | 5.4726 | 8.3750 | 8.100 | 9.671 | 9.234 | 3.538 | 3.338 | 2.337 | -- | 11.500 | 1.250 | 0.154 |
| 5 3/4 | 5.7500 | 5.7500 | 5.7225 | 8.7500 | 8.462 | 10.104 | 9.647 | 3.729 | 3.521 | 2.465 | -- | 12.000 | 1.250 | 0.161 |
| 6 | 6.0000 | 6.000 | 5.9725 | 9.1250 | 8.825 | 10.537 | 10.060 | 3.858 | 3.642 | 2.549 | -- | 12.500 | 1.250 | 0.168 |
Note:
Wrenching Height J, is a distance measured from the bearing surface up the side of the head at the corners. The width across corner shall be within specified limits for the full wrenching height.