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Oster Power Threading Handbook

Reference Charts

Bolt Thread Size Chart

Size Threads Per Inch Class Thread Major Diameter
Min
Max
Pitch Diameter
Min
Max
Minor Diameter
1/4 20 2A 0.2489 0.2408 0.2164 0.2127 0.1876
28 2A 0.2490 0.2425 0.2258 0.2225 0.2052
5/16 18 2A 0.3113 0.3026 0.2752 0.2712 0.2431
24 2A 0.3114 0.3042 0.2843 0.2806 0.2603
3/8 16 2A 0.3737 0.3643 0.3331 0.3287 0.2970
24 2A 0.3739 0.3667 0.3468 0.3430 0.3228
7/16 14 2A 0.4361 0.4258 0.3897 0.3850 0.3485
20 2A 0.4362 0.4281 0.4237 0.3995 0.3749
1/2 13 2A 0.4985 0.4876 0.4485 0.4435 0.4041
20 2A 0.4987 0.4906 0.4662 0.4619 0.4374
9/16 12 2A 0.5609 0.5495 0.5068 0.5016 0.4587
18 2A 0.5611 0.5524 0.5250 0.5205 0.4929
5/8 11 2A 0.6234 0.6113 0.5644 0.5589 0.5119
18 2A 0.6236 0.6149 0.5875 0.5828 0.5449
3/4 10 2A 0.7482 0.7353 0.6832 0.6773 0.6255
16 2A 0.7485 0.7391 0.7079 0.7029 0.6718
7/8 9 2A 0.8731 0.8592 0.8009 0.7946 0.7368
14 2A 0.8734 0.8631 0.8270 0.8216 0.7858
1 8 2A 0.9980 0.9830 0.9168 0.9100 0.8446
12 2A 0.9982 0.9868 0.9441 0.9382 0.8960

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Standard Pipe Sizes

Nominal Size Schedule Number Outside Diameter Inside Diameter Wall Thickness Inside Area Weight Per Ft. Metal Area
1/8 40 0.405 0.269 0.068 0.057 0.245 0.072
80 0.405 0.215 0.095 0.036 0.315 0.093
1/4 40 0.540 0.364 0.088 0.104 0.425 0.125
80 0.540 0.302 0.119 0.072 0.535 0.157
3/8 40 0.675 0.493 0.091 0.191 0.568 0.167
80 0.675 0.423 0.126 0.141 0.739 0.217
1/2 40 0.840 0.622 0.109 0.304 0.851 0.250
80 0.840 0.546 0.147 0.234 1.088 0.320
3/4 40 1.050 0.824 0.113 0.533 1.131 0.333
80 1.050 0.742 0.154 0.432 1.474 0.433
1 40 1.315 1.049 0.133 0.864 1.679 0.494
80 1.315 0.957 0.179 0.719 2.172 0.639
1-1/4 40 1.660 1.380 0.140 1.496 2.273 0.668
80 1.660 1.278 0.191 1.283 2.996 0.881
1-1/2 40 1.900 1.610 0.145 2.036 2.718 0.799
80 1.900 1.500 0.200 1.767 3.631 1.068
2 40 2.375 2.067 0.154 3.356 3.653 1.074
80 2.375 1.939 0.218 2.953 5.022 1.477
2-1/2 40 2.875 2.469 0.203 4.788 5.792 1.704
80 2.875 2.323 0.276 4.238 7.660 2.253
3 40 3.500 3.068 0.216 7.393 7.575 2.228
80 3.500 2.900 0.300 6.605 10.252 3.016
3-1/2 40 4.000 3.548 0.226 9.887 9.108 2.679
80 4.000 3.364 0.318 8.888 12.504 3.678
4 40 4.500 4.026 0.237 12.730 10.789 3.174
80 4.500 3.826 0.337 11.497 14.982 4.407
5 40 5.563 5.047 0.258 20.006 14.615 4.299
80 5.563 4.813 0.375 18.194 20.776 6.111
6 40 6.625 6.065 0.280 28.890 18.971 5.580
80 6.625 5.761 0.432 26.607 28.570 8.404
8 40 8.625 7.981 0.322 50.027 28.548 8.397
80 8.625 7.625 0.500 45.664 43.382 12.761
10 40 10.750 10.020 0.365 78.854 40.474 11.905
80 10.750 9.750 0.500 74.662 54.726 16.098
12 40 12.750 11.938 0.406 111.932 53.512 15.741
80 12.750 11.750 0.500 108.434 65.402 19.238

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National Pipe Thread

Basic Dimensons, American Standard Taper Pipe Threads, NPT

For all dimensions se corresponding reference letters in table. Angle between sides of thread is 60 degrees. Taper of thread on diameter is 3/4 inches per foot. Angle of taper with centerline is 1° 47' 24" (1.7899°). The basic maximum thread height, h of the truncated thread is 0.8 x (pitch of thread). The crest and root are truncated a minimum of 0.033 x (pitch) for all pitches.

Nominal Pipe Size Outside Diameter of Pipe,
D
Threads per Inch,
n
Pitch of Thread,
P
Pitch Dia, at Beginning of External Thread,
E0
Handtight Engagement

Length",
L1
Diameter,
E1
Handtight Engagement

Length",
L2
Diameter,
E2
1/16 0.3125 27 0.03704 0.27118 0.160 0.28118 0.2611 0.28750
1/8 0.405 27 0.03704 0.36351 0.1615 0.37360 0.2639 0.38000
1/4 0.540 18 0.05556 0.47739 0.2278 0.49163 0.4018 0.50250
3/8 0.675 18 0.05556 0.61201 0.240 0.62701 0.4078 0.63750
1/2 0.840 14 0.07143 0.75843 0.320 0.77843 0.5337 0.79179
3/4 1.050 14 0.07143 0.96768 0.339 0.98887 0.5457 1.00179
1 1.315 11.5 0.08696 1.21363 0.400 1.23863 0.6828 1.25630
1-1/4 1.660 11.5 0.08696 1.55713 0.420 1.58338 0.7068 1.60130
1-1/2 1.900 11.5 0.08696 1.79609 0.420 1.82234 0.7235 1.84130
2 2.375 11.5 0.08696 2.26902 0.436 2.29627 0.7565 2.31630
2-1/2 2.875 8 0.12500 2.71953 0.682 2.76216 1.1375 2.79062
3 3.5 8 0.12500 3.34062 0.766 3.38850 1.2000 3.41562
3-1/2 4 8 0.12500 3.83750 0.821 3.88881 1.2500 3.91562
4 4.5 8 0.12500 4.33438 0.844 4.38712 1.3000 4.41562
5 5.563 8 0.12500 5.39073 0.937 5.44929 1.4063 5.47862
6 6.625 8 0.12500 6.44609 0.958 6.50597 1.5125 6.54062
8 8.625 8 0.12500 8.43359 1.063 8.50003 1.7125 8.54062
10 10.750 8 0.12500 10.54531 1.210 10.62094 1.9250 10.66562
12 12.750 8 0.12500 12.53281 1.360 12.61781 2.1250 12.66562

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Profiles For Various Standard Threads

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