Page 313 - Mechanical Engineer's Data Handbook

GENERAL DATA 301
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0.2.7 Unified screw threads

Coarse series (UNC) Fine series (UNF)
Nominal
major Area at bottom Area at bottom
diameter No. threads of threads No. threads of threads
Size per per
designation in. mm inch in.’ mm2 inch in.’ mm2
0 0.0600 1.524 80 0.00151 0.974
1 0.0730 1.854 64 0.002 18 1.406 72 0.00237 1.529
2 0.0860 2.184 56 0.00310 2.000 64 0.00339 2.187
3 0.0990 2.5 15 48 0.00406 2.619 56 0.0045 1 2.910
4 0.1 120 2.845 40 0.00496 3.200 48 0.00566 3.652
5 0.1250 3.175 40 0.00672 4.335 44 0.00716 4.619
6 0.1380 3.505 32 0.00745 4.806 40 0.00874 5.639
8 0.1640 4.166 32 0.01 196 7.716 36 0.01285 8.290
10 0.1900 4.826 24 0.01450 9.355 32 0.0175 11.29
12 0.2 160 5.486 24 0.0206 13.29 28 0.0226 14.58
1 14 0.2500 6.350 20 0.0269 17.35 28 0.0326 21.03
5/16 0.3125 7.938 18 0.0454 29.29 24 0.0524 33.81
318 0.375 9.525 16 0.0678 43.74 24 0.0809 52.19
7/16 0.4375 11.11 14 0.0933 60.19 20 0.1090 70.32
112 0.5000 12.70 13 0.1257 81.10 20 0.1485 95.87
9/16 0.5625 14.29 12 0.162 104.5 18 0.1890 121.9
518 0.6250 15.88 11 0.202 130.3 18 0.240 154.8
314 0.7500 19.05 10 0.302 194.8 16 0.35 1 226.5
718 0.8750 22.23 9 0.419 270.3 14 0.480 309.7
1 1 .m 25.40 8 0.551 355.5 12 0.625 403.2
1; 1.2500 3 1.75 7 0.890 574.2 12 1.024 660.6
1+ 1 .5000 38.10 6 1.294 834.8 12 1.260 812.9

8.2.0 Pipe threads

BSP pipe threads (BS 2779: 1973) - Whitworth thread form

Nominal size Threads per Pitch Major diameter Minor diameter
(in.) inch (mm) (mm) (mm )

28 0.907 7.723 6.561
28 0.907 9.728 8.566
19 1.337 13.157 1 1.445
19 1.337 16.662 14.950
14 1.814 20.955 18.631
14 1.814 22.91 1 20.587
14 1.814 26.441 24.1 17
14 1.814 30.201 27.877
11 2.309 33.249 30.291
11 2.309 37.897 34.939
11 2.309 41.910 38.952