Machinery's Handbook, 31st Edition
2090 American Pipe Threads Table 1a. Basic Dimensions, American National Standard Taper Pipe Threads, NPT ANSI/ASME B1.20.1-2013 (R2018) L 4 V Imperfect Threads due to Chamfer on die
L 2
L 5
2 p
Taper of Thread 1 in 16 Measured on Diameter
L 3
L 1
E 5
E 2
E 1
D
E 0
E 3
For all dimensions, see corresponding reference letter in table. Angle between sides of thread is 60 degrees. Taper of thread, on diameter, is 3 ∕ 4 inch per foot. Angle of taper with center line is 1 ° 47 ′ . The basic maximum thread height, h , of the truncated thread is 0.8 × pitch of thread. The crest and root are truncated a minimum of 0.033 × pitch for all pitches. For maximum depth of truncation, see Table 2.
Handtight Engagement
Effective Thread, External
Pitch Diameter at Beginning of External Thread, E 0
Outside Dia. of Pipe, D
Threads per Inch, n
Pitch of Thread, p 0.03704 0.03704 0.05556 0.05556 0.07143 0.07143 0.08696 0.08696 0.08696 0.08696 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500 0.12500
Length, a L 1
Dia., b E 1
Length, c L 2
Dia., E 2
Nominal Pipe Size
Inch
Inch
0.3125 27
0.27118 0.36351 0.47739 0.61201 0.75843 0.96768 1.21363 1.55713 1.79609 2.26902 2.71953 3.34062 3.83750 4.33438 5.39073 6.44609 8.43359 10.54531 12.53281 13.77500 15.76250 17.75000 19.73750 23.71250
0.160
0.28118
0.2611 0.2639 0.4018 0.4078 0.5337 0.5457 0.6828 0.7068 0.7235 0.7565 1.1375 1.2000 1.2500 1.3000 1.4063 1.5125 1.7125 1.9250 2.1250 2.2500 2.4500 2.6500 2.8500 3.2500
0.28750 0.38000 0.50250 0.63750 0.79179 1.00179 1.25630 1.60130 1.84130 2.31630 2.79062 3.41562 3.91562 4.41562 5.47862 6.54062 8.54062 10.66562 12.66562 13.91562 15.91562 17.91562 19.91562 23.91562
1 ∕ 16
0.405 0.540 0.675 0.840 1.050 1.315 1.660 1.900 2.375 2.875 3.500 4.000 4.500 5.563 6.625 8.625
27 18 18 14 14
0.1615 0.37360 0.2278 0.49163
1 ∕ 8 1 ∕ 4 3 ∕ 8 1 ∕ 2 3 ∕ 4
0.240 0.320 0.339 0.400 0.420 0.420 0.436 0.682 0.766 0.821 0.844 0.937 0.958 1.063
0.62701 0.77843 0.98887 1.23863 1.58338 1.82234 2.29627 2.76216 3.38850 3.88881 4.38712 5.44929 6.50597 8.50003
1
11 1 ∕ 2 11 1 ∕ 2 11 1 ∕ 2 11 1 ∕ 2
1 1 ∕ 4 1 1 ∕ 2
2
8 8 8 8 8 8 8 8 8 8 8 8 8 8
2 1 ∕ 2
3
3 1 ∕ 2
4 5 6 8
10 12
10.750 12.750
1.210 10.62094 1.360 12.61781 1.562 13.87262 1.812 15.87575 2.000 17.87500 2.125 19.87031 2.375 23.86094
14 OD 14.000 16 OD 16.000 18 OD 18.000 20 OD 20.000 24 OD 24.000
a Also length of thin ring gage and length from gaging notch to small end of plug gage. b Also pitch diameter at gaging notch (handtight plane). c Also length of plug gage.
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