ASME B18.31.2 Clamping Type Reduced Body Studs
ASME B18.31.2 Clamping Type Reduced Body Studs Standard provides
dimensional and general data for double-end studs recognized as American National Standard in inch
dimensions.
Double-end (clamping type — identical ends) stud: a stud with screw threads of the same
length and configuration on each end and used to clamp two bodies together with nuts on both ends.
Reduced body studs have a shank diameter smaller than the nominal thread diameter, which can
improve elasticity and reduce stress concentration in certain bolting applications.
The inclusion of dimensional data in ASME B18.31.2 Standard is not intended to imply that
all products described are stock production items. Consumers should consult with suppliers
concerning
availability of products.
ASME B18.31.2 Dimensions for Clamping Type Reduced Body Studs (mm)
| Nominal Size |
Diameter, D | Umax = 2 Thread Pitches | Maximum Body Diameter, DR , for Reduced-Body Studs | Minimum Body Diameter, DR , for Reduced-Body Studs | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| UNC Threads | UNF Threads | 8UN Threads | UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads | UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads | ||
| ¼ | 6.350 | 2.540 | 1.803 | ... | 6.121 | 6.172 | … | 5.410 | 5.664 | … |
| 5/16 | 7.938 | 2.819 | 2.108 | ... | 7.696 | 7.722 | … | 6.883 | 7.137 | … |
| 3/8 | 9.525 | 3.175 | 2.108 | ... | 9.246 | 9.322 | … | 8.357 | 8.712 | … |
| 7/16 | 11.113 | 3.632 | 2.540 | ... | 10.820 | 10.871 | … | 9.779 | 10.160 | … |
| ½ | 12.700 | 3.912 | 2.540 | ... | 12.395 | 12.471 | … | 11.278 | 11.735 | … |
| 9/16 | 14.288 | 4.242 | 2.819 | ... | 13.970 | 14.021 | … | 12.751 | 13.233 | … |
| 5/8 | 15.875 | 4.623 | 2.819 | ... | 15.519 | 15.621 | … | 14.199 | 14.808 | … |
| ¾ | 19.050 | 5.080 | 3.175 | ... | 18.669 | 18.771 | … | 17.196 | 17.856 | … |
| 7/8 | 22.225 | 5.639 | 3.632 | ... | 21.819 | 21.920 | … | 20.193 | 20.879 | … |
| 1 | 25.400 | 6.350 | 4.242 | ... | 24.968 | 25.070 | … | 23.114 | 23.825 | … |
| 1⅛ | 28.575 | 7.264 | 4.242 | 6.350 | 28.092 | 28.245 | 28.143 | 25.984 | 27.000 | 26.289 |
| 1¼ | 31.750 | 7.264 | 4.242 | 6.350 | 31.267 | 31.420 | 31.318 | 29.159 | 30.175 | 29.464 |
| 1⅜ | 34.925 | 8.458 | 4.242 | 6.350 | 34.392 | 34.595 | 34.493 | 31.902 | 33.350 | 32.614 |
| 1½ | 38.100 | 8.458 | 4.242 | 6.350 | 37.567 | 37.770 | 37.668 | 35.077 | 36.525 | 35.789 |
| 1⅝ | 41.275 | ... | ... | 6.350 | … | … | 40.843 | … | … | 38.964 |
| 1¾ | 44.450 | 10.160 | ... | 6.350 | 43.866 | … | 44.018 | 40.869 | … | 42.139 |
| 1⅞ | 47.625 | ... | ... | 6.350 | … | … | 47.193 | … | … | 45.314 |
| 2 | 50.800 | 11.278 | ... | 6.350 | 50.165 | … | 50.368 | 46.812 | … | 48.489 |
| 2¼ | 57.150 | 11.278 | ... | 6.350 | 56.515 | … | 56.718 | 53.162 | … | 54.813 |
| 2½ | 63.500 | 12.700 | ... | 6.350 | 62.814 | … | 63.068 | 59.030 | … | 61.163 |
| 2¾ | 69.850 | 12.700 | ... | 6.350 | 69.164 | … | 69.418 | 65.380 | … | 67.513 |
| 3 | 76.200 | 12.700 | ... | 6.350 | 75.514 | … | 75.743 | 71.730 | … | 73.863 |
| 3¼ | 82.550 | 12.700 | ... | 6.350 | 81.864 | … | 82.093 | 78.054 | … | 80.213 |
| 3½ | 88.900 | 12.700 | ... | 6.350 | 88.214 | … | 88.443 | 84.404 | … | 86.538 |
| 3¾ | 95.250 | 12.700 | ... | 6.350 | 90.754 | … | 92.888 | 94.564 | … | 94.793 |
| 4 | 101.600 | 12.700 | ... | 6.350 | 97.104 | … | 99.238 | 100.914 | … | 101.143 |
ASME B18.31.2 Clamping Type Reduced Body Studs Length Tolerances (mm)
| Range, LT | Tolerances |
|---|---|
| From 19.05 through 63.5 | ±1.016 |
| Over 63.5 through 101.6 | ±2.032 |
| Over 101.6 through 203.2 | ±2.540 |
| Over 203.2 through 406.4 | ±3.048 |
| Over 406.4 | ±4.572 |
ASME B18.31.2 Dimensions for Clamping Type Reduced Body Studs (Inch)
| Nominal Size |
Diameter, D |
Umax = 2 Thread Pitches | Maximum Body Diameter, DR , for Reduced- Body Studs |
Minimum Body Diameter, DR , for Reduced- Body Studs |
||||||
|---|---|---|---|---|---|---|---|---|---|---|
| UNC Threads | UNF Threads | 8UN Threads | UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads | UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads | ||
| ¼ | 0.2500 | 0.100 | 0.071 | ... | 0.241 | 0.243 | … | 0.213 | 0.223 | … |
| 5/16 | 0.3125 | 0.111 | 0.083 | ... | 0.303 | 0.304 | … | 0.271 | 0.281 | … |
| 3/8 | 0.3750 | 0.125 | 0.083 | ... | 0.364 | 0.367 | … | 0.329 | 0.343 | … |
| 7/16 | 0.4375 | 0.143 | 0.100 | ... | 0.426 | 0.428 | … | 0.385 | 0.4 | … |
| ½ | 0.5000 | 0.154 | 0.100 | ... | 0.488 | 0.491 | … | 0.444 | 0.462 | … |
| 9/16 | 0.5625 | 0.167 | 0.111 | ... | 0.550 | 0.552 | … | 0.502 | 0.521 | … |
| 5/8 | 0.6250 | 0.182 | 0.111 | ... | 0.611 | 0.615 | … | 0.559 | 0.583 | … |
| ¾ | 0.7500 | 0.200 | 0.125 | ... | 0.735 | 0.739 | … | 0.677 | 0.703 | … |
| 7/8 | 0.8750 | 0.222 | 0.143 | ... | 0.859 | 0.863 | … | 0.795 | 0.822 | … |
| 1 | 1.0000 | 0.250 | 0.167 | ... | 0.983 | 0.987 | … | 0.91 | 0.938 | … |
| 1⅛ | 1.1250 | 0.286 | 0.167 | 0.250 | 1.106 | 1.112 | 1.108 | 1.023 | 1.063 | 1.035 |
| 1¼ | 1.2500 | 0.286 | 0.167 | 0.250 | 1.231 | 1.237 | 1.233 | 1.148 | 1.188 | 1.16 |
| 1⅜ | 1.3750 | 0.333 | 0.167 | 0.250 | 1.354 | 1.362 | 1.358 | 1.256 | 1.313 | 1.284 |
| 1½ | 1.5000 | 0.333 | 0.167 | 0.250 | 1.479 | 1.487 | 1.483 | 1.381 | 1.438 | 1.409 |
| 1⅝ | 1.6250 | ... | ... | 0.250 | … | … | 1.608 | … | … | 1.534 |
| 1¾ | 1.7500 | 0.400 | ... | 0.250 | 1.727 | … | 1.733 | 1.609 | … | 1.659 |
| 1⅞ | 1.8750 | ... | ... | 0.250 | … | … | 1.858 | … | … | 1.784 |
| 2 | 2.0000 | 0.444 | ... | 0.250 | 1.975 | … | 1.983 | 1.843 | … | 1.909 |
| 2¼ | 2.2500 | 0.444 | ... | 0.250 | 2.225 | … | 2.233 | 2.093 | … | 2.158 |
| 2½ | 2.5000 | 0.500 | ... | 0.250 | 2.473 | … | 2.483 | 2.324 | … | 2.408 |
| 2¾ | 2.7500 | 0.500 | ... | 0.250 | 2.723 | … | 2.733 | 2.574 | … | 2.658 |
| 3 | 3.0000 | 0.500 | ... | 0.250 | 2.973 | … | 2.982 | 2.824 | … | 2.908 |
| 3¼ | 3.2500 | 0.500 | ... | 0.250 | 3.223 | … | 3.232 | 3.073 | … | 3.158 |
| 3½ | 3.5000 | 0.500 | ... | 0.250 | 3.473 | … | 3.482 | 3.323 | … | 3.407 |
| 3¾ | 3.7500 | 0.500 | ... | 0.250 | 3.573 | … | 3.657 | 3.723 | … | 3.732 |
| 4 | 4.0000 | 0.500 | ... | 0.250 | 3.823 | … | 3.907 | 3.973 | … | 3.982 |
ASME B18.31.2 Clamping Type Reduced Body Studs Length Tolerances
| Range, LT | Tolerances |
|---|---|
| From ¾ through 2½ | ±0.04 |
| Over 2½ through 4 | ±0.08 |
| Over 4 through 8 | ±0.10 |
| Over 8 through 16 | ±0.12 |
| Over 16 | ±0.18 |
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