ASME B18.31.2 Tap End Reduced Body Studs
ASME B18.31.2 Tap-End Reduced Body Studs Standard covers
dimensional and general data for tap-end studs recognized as American National Standard in inch
dimensions.
Double-end (tap-end type) stud: a stud designed to be installed in a tapped hole with
different threaded lengths on each end.
Reduced body studs have a shank diameter smaller than the nominal thread diameter, which
allows
greater flexibility and can help reduce bending stresses in certain applications.
For the tap end of the studs, both regular unified threads and interference-fit threads are
covered.
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 Tap End Reduced Body Studs (mm)
| Nominal Size |
Diameter, D |
Minimum Nut-End Full Thread Length, Bmin |
Maximum Body Diameter, DR , for Reduced- Body Studs |
Minimum Body Diameter, DR , for Reduced- Body Studs |
||||||
|---|---|---|---|---|---|---|---|---|---|---|
| L ≤ 254 mm (10 in) |
254 < L ≤ 406.4 mm (10 < L ≤ 16 in) |
L > 406.4 mm (16 in) |
UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads |
UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads | ||
| ¼ | 6.350 | 19.050 | 25.400 | 38.100 | 6.121 | 6.172 | … | 5.410 | 5.664 | … |
| 5/16 | 7.938 | 22.225 | 28.575 | 41.275 | 7.696 | 7.722 | … | 6.883 | 7.137 | … |
| 3/8 | 9.525 | 25.400 | 31.750 | 44.450 | 9.246 | 9.322 | … | 8.357 | 8.712 | … |
| 7/16 | 11.112 | 28.575 | 34.925 | 47.625 | 10.820 | 10.871 | … | 9.779 | 10.160 | … |
| ½ | 12.700 | 31.750 | 38.100 | 50.800 | 12.395 | 12.471 | … | 11.278 | 11.735 | … |
| 9/16 | 14.287 | 34.925 | 41.275 | 53.975 | 13.970 | 14.021 | … | 12.751 | 13.233 | … |
| 5/8 | 15.875 | 38.100 | 44.450 | 57.150 | 15.519 | 15.621 | … | 14.199 | 14.808 | … |
| ¾ | 19.050 | 44.450 | 50.800 | 63.500 | 18.669 | 18.771 | … | 17.196 | 17.856 | … |
| 7/8 | 22.225 | 50.800 | 57.150 | 69.850 | 21.819 | 21.920 | … | 20.193 | 20.879 | … |
| 1 | 25.400 | 57.150 | 63.500 | 76.200 | 24.968 | 25.070 | … | 23.114 | 23.825 | … |
| 1⅛ | 28.575 | 63.500 | 69.850 | 82.550 | 28.092 | 28.245 | 28.143 | 25.984 | 27.000 | 26.289 |
| 1¼ | 31.750 | 69.850 | 76.200 | 88.900 | 31.267 | 31.420 | 31.318 | 29.159 | 30.175 | 29.464 |
| 1⅜ | 34.925 | 76.200 | 82.550 | 95.250 | 34.392 | 34.595 | 34.493 | 31.902 | 33.350 | 32.614 |
| 1½ | 38.100 | 82.550 | 88.900 | 101.600 | 37.567 | 37.770 | 37.668 | 35.077 | 36.525 | 35.789 |
| 1⅝ | 41.275 | 88.900 | 95.250 | 107.950 | … | … | 40.843 | … | … | 38.964 |
| 1¾ | 44.450 | 95.250 | 101.600 | 114.300 | 43.866 | … | 44.018 | 40.869 | … | 42.139 |
| 1⅞ | 47.625 | 101.600 | 107.950 | 120.650 | … | … | 47.193 | … | … | 45.314 |
| 2 | 50.800 | 107.950 | 114.300 | 127.000 | 50.165 | … | 50.368 | 46.812 | … | 48.489 |
| 2¼ | 57.150 | 120.650 | 127.000 | 139.700 | 56.515 | … | 56.718 | 53.162 | … | 54.813 |
| 2½ | 63.500 | 133.350 | 139.700 | 152.400 | 62.814 | … | 63.068 | 59.030 | … | 61.163 |
| 2¾ | 69.850 | 146.050 | 152.400 | 165.100 | 69.164 | … | 69.418 | 65.380 | … | 67.513 |
| 3 | 76.200 | … | 165.100 | 177.800 | 75.514 | … | 75.743 | 71.730 | … | 73.863 |
| 3¼ | 82.550 | … | 177.800 | 190.500 | 81.864 | … | 82.093 | 78.054 | … | 80.213 |
| 3½ | 88.900 | … | 190.500 | 203.200 | 88.214 | … | 88.443 | 84.404 | … | 86.538 |
| 3¾ | 95.250 | … | 203.200 | 215.900 | 94.564 | … | 94.793 | 90.754 | … | 92.888 |
| 4 | 101.600 | … | 215.900 | 228.600 | 100.914 | … | 101.143 | 97.104 | … | 99.238 |
ASME B18.31.2 Tap End Stud Reduced Body Length Tolerances
| Range, LT | Tap-End Studs Tolerance |
|---|---|
| From 19.05 through 63.5 | ±0.762 |
| Over 63.5 through 101.6 | ±1.270 |
| Over 101.6 through 203.2 | ±2.032 |
| Over 203.2 through 406.4 | ±2.540 |
| Over 406.4 | ±3.048 |
ASME B18.31.2 Dimensions for Tap End Reduced Body Studs (Inch)
| Nominal Size |
Diameter, D |
Minimum Nut-End Full Thread Length, Bmin |
Maximum Body Diameter, DR , for Reduced- Body Studs |
Minimum Body Diameter, DR , for Reduced- Body Studs |
||||||
|---|---|---|---|---|---|---|---|---|---|---|
| L ≤ 10 | 10 < L ≤ 16 | L > 16 | UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads |
UNC and NC-5 HF Threads |
UNF Threads |
8UN Threads | ||
| ¼ | 0.2500 | 0.750 | 1.000 | 1.500 | 0.241 | 0.243 | … | 0.213 | 0.223 | … |
| 5/16 | 0.3125 | 0.875 | 1.125 | 1.625 | 0.303 | 0.304 | … | 0.271 | 0.281 | … |
| 3/8 | 0.3750 | 1.000 | 1.250 | 1.750 | 0.364 | 0.367 | … | 0.329 | 0.343 | … |
| 7/16 | 0.4375 | 1.125 | 1.375 | 1.875 | 0.426 | 0.428 | … | 0.385 | 0.4 | … |
| ½ | 0.5000 | 1.250 | 1.500 | 2.000 | 0.488 | 0.491 | … | 0.444 | 0.462 | … |
| 9/16 | 0.5625 | 1.375 | 1.625 | 2.125 | 0.550 | 0.552 | … | 0.502 | 0.521 | … |
| 5/8 | 0.6250 | 1.500 | 1.750 | 2.250 | 0.611 | 0.615 | … | 0.559 | 0.583 | … |
| ¾ | 0.7500 | 1.750 | 2.000 | 2.500 | 0.735 | 0.739 | … | 0.677 | 0.703 | … |
| 7/8 | 0.8750 | 2.000 | 2.250 | 2.750 | 0.859 | 0.863 | … | 0.795 | 0.822 | … |
| 1 | 1.0000 | 2.250 | 2.500 | 3.000 | 0.983 | 0.987 | … | 0.91 | 0.938 | … |
| 1⅛ | 1.1250 | 2.500 | 2.750 | 3.250 | 1.106 | 1.112 | 1.108 | 1.023 | 1.063 | 1.035 |
| 1¼ | 1.2500 | 2.750 | 3.000 | 3.500 | 1.231 | 1.237 | 1.233 | 1.148 | 1.188 | 1.16 |
| 1⅜ | 1.3750 | 3.000 | 3.250 | 3.750 | 1.354 | 1.362 | 1.358 | 1.256 | 1.313 | 1.284 |
| 1½ | 1.5000 | 3.250 | 3.500 | 4.000 | 1.479 | 1.487 | 1.483 | 1.381 | 1.438 | 1.409 |
| 1⅝ | 1.6250 | 3.500 | 3.750 | 4.250 | … | … | 1.608 | … | … | 1.534 |
| 1¾ | 1.7500 | 3.750 | 4.000 | 4.500 | 1.727 | … | 1.733 | 1.609 | … | 1.659 |
| 1⅞ | 1.8750 | 4.000 | 4.250 | 4.750 | … | … | 1.858 | … | … | 1.784 |
| 2 | 2.0000 | 4.250 | 4.500 | 5.000 | 1.975 | … | 1.983 | 1.843 | … | 1.909 |
| 2¼ | 2.2500 | 4.750 | 5.000 | 5.500 | 2.225 | … | 2.233 | 2.093 | … | 2.158 |
| 2½ | 2.5000 | 5.250 | 5.500 | 6.000 | 2.473 | … | 2.483 | 2.324 | … | 2.408 |
| 2¾ | 2.7500 | 5.750 | 6.000 | 6.500 | 2.723 | … | 2.733 | 2.574 | … | 2.658 |
| 3 | 3.0000 | … | 6.500 | 7.000 | 2.973 | … | 2.982 | 2.824 | … | 2.908 |
| 3¼ | 3.2500 | … | 7.000 | 7.500 | 3.223 | … | 3.232 | 3.073 | … | 3.158 |
| 3½ | 3.5000 | … | 7.500 | 8.000 | 3.473 | … | 3.482 | 3.323 | … | 3.407 |
| 3¾ | 3.7500 | … | 8.000 | 8.500 | 3.723 | … | 3.732 | 3.573 | … | 3.657 |
| 4 | 4.0000 | … | 8.500 | 9.000 | 3.973 | … | 3.982 | 3.823 | … | 3.907 |
ASME B18.31.2 Tap End Reduced Body Studs Length Tolerances (Inch)
| Range, LT | Tap-End Reduced Body Studs Tolerance |
|---|---|
| From 3/4 through 2 1/2 | ±0.03 |
| Over 2 1/2 through 4 | ±0.05 |
| Over 4 through 8 | ±0.08 |
| Over 8 through 16 | ±0.10 |
| Over 16 | ±0.12 |
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