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Standard Taper Pipe Threads NPT Basic Dimensions, American National Standard
Basic Dimensions, American National Standard Taper Pipe Threads, NPT
Notes:
|
ANSI/ASME B1.20.1-1983 (R2006)
All Dimensions Given in inches
Nominal Pipe Size |
Wrench Makeup Length for Internal Thread |
Vanish Thread, (3.47 thds.), V |
Overall Length External Thread, L4 |
Nominal Perfect External Threadsa |
Height of Thread, h |
Basic Minor Dia. at Small End of Pipe,b K0 |
||
Length,c L3 |
Dia., E3 |
Length, L5 |
Dia., E5 |
|||||
1⁄16 |
0.1111 |
0.26424 |
0.1285 |
0.3896 |
0.1870 |
0.28287 |
0.02963 |
0.2416 |
1⁄8 |
0.1111 |
0.35656 |
0.1285 |
0.3924 |
0.1898 |
0.37537 |
0.02963 |
0.3339 |
1⁄4 |
0.1667 |
0.46697 |
0.1928 |
0.5946 |
0.2907 |
0.49556 |
0.04444 |
0.4329 |
3⁄8 |
0.1667 |
0.60160 |
0.1928 |
0.6006 |
0.2967 |
0.63056 |
0.04444 |
0.5676 |
1⁄2 |
0.2143 |
0.74504 |
0.2478 |
0.7815 |
0.3909 |
0.78286 |
0.05714 |
0.7013 |
3⁄4 |
0.2143 |
0.95429 |
0.2478 |
0.7935 |
0.4029 |
0.99286 |
0.05714 |
0.9105 |
1 |
0.2609 |
1.19733 |
0.3017 |
0.9845 |
0.5089 |
1.24543 |
0.06957 |
1.1441 |
11⁄4 |
0.2609 |
1.54083 |
0.3017 |
1.0085 |
0.5329 |
1.59043 |
0.06957 |
1.4876 |
11⁄2 |
0.2609 |
1.77978 |
0.3017 |
1.0252 |
0.5496 |
1.83043 |
0.06957 |
1.7265 |
2 |
0.2609 |
2.25272 |
0.3017 |
1.0582 |
0.5826 |
2.30543 |
0.06957 |
2.1995 |
2-1⁄2 |
0.2500d |
2.70391 |
0.4337 |
1.5712 |
0.8875 |
2.77500 |
0.100000 |
2.6195 |
3 |
0.2500d |
3.32500 |
0.4337 |
1.6337 |
0.9500 |
3.40000 |
0.100000 |
3.2406 |
3-1⁄2 |
0.2500 |
3.82188 |
0.4337 |
1.6837 |
1.0000 |
3.90000 |
0.100000 |
3.7375 |
4 |
0.2500 |
4.31875 |
0.4337 |
1.7337 |
1.0500 |
4.40000 |
0.100000 |
4.2344 |
5 |
0.2500 |
5.37511 |
0.4337 |
1.8400 |
1.1563 |
5.46300 |
0.100000 |
5.2907 |
6 |
0.2500 |
6.43047 |
0.4337 |
1.9462 |
1.2625 |
6.52500 |
0.100000 |
6.3461 |
8 |
0.2500 |
8.41797 |
0.4337 |
2.1462 |
1.4625 |
8.52500 |
0.100000 |
8.3336 |
10 |
0.2500 |
10.52969 |
0.4337 |
2.3587 |
1.6750 |
10.65000 |
0.100000 |
10.4453 |
12 |
0.2500 |
12.51719 |
0.4337 |
2.5587 |
1.8750 |
12.65000 |
0.100000 |
12.4328 |
14 OD |
0.2500 |
13.75938 |
0.4337 |
2.6837 |
2.0000 |
13.90000 |
0.100000 |
13.6750 |
16 OD |
0.2500 |
15.74688 |
0.4337 |
2.8837 |
2.2000 |
15.90000 |
0.100000 |
15.6625 |
18 OD |
0.2500 |
17.73438 |
0.4337 |
3.0837 |
2.4000 |
17.90000 |
0.100000 |
17.6500 |
20 OD |
0.2500 |
19.72188 |
0.4337 |
3.2837 |
2.6000 |
19.90000 |
0.100000 |
19.6375 |
24 OD |
0.2500 |
23.69688 |
0.4337 |
3.6837 |
3.0000 |
23.90000 |
0.100000 |
23.6125 |
aThe length L5 from the end of the pipe determines the plane beyond which the thread form is imperfect
at the crest. The next two threads are perfect at the root. At this plane the cone formed by the crests of the thread intersects the cylinder forming the external surface of the pipe. L5 = L2 − 2p.
b Given as information for use in selecting tap drills.
cThree threads for 2-inch size and smaller; two threads for larger sizes.
d Military Specification MIL-P-7105 gives the wrench makeup as three threads for 3 in. and smaller. The E3 dimensions are then as follows: Size 21⁄2 in., 2.69609 and size 3 in., 3.31719.
The basic dimensions of the ANSI Standard Taper Pipe Thread are given in inches to four or five decimal places. While this implies a greater degree of precision than is ordinarily attained, these dimensions are the basis of gage dimensions and are so expressed for the purpose of eliminating errors in computations.