What is the NPT pipe thread according to ANSI B 1.20.1-1983?

The NPT pipe thread is a self-sealing thread with a flank angle of 60°, used for pressure-tight connections in pipeline systems.

Data Table for NPT Pipe Threads ANSI B 1.20.1-1983

Here you will find the dimensions of the self-sealing NPT pipe thread according to ANSI B 1.20.1-1983 with a flank angle of 60°.


Thread Pitch Diameter outside
[mm]
Core hole diameter 
at the thin end of the pipe
 [mm]
Number of threads
per 25.4 mm
1/16“ – 27 NPT 0.941 7.895 6.00 27
1/8“ – 27 NPT 0.941 10.242 8.25 27
1/4“ – 18 NPT 1.411 13.616 10.70 18
3/8“ – 18 NPT 1.411 17.055 14.10 18
1/2“ – 14 NPT 1.814 21.223 17.40 14
3/4“ – 14 NPT 1.814 26.568 22.60 14
1“ – 11 1/2 NPT 2.209 33.228 28.50 11.5
1 1/4“ – 11 1/2 NPT 2.209 41.985 37.00 11.5
1 1/2“ – 11 1/2 NPT 2.209 48.054 43.50 11.5
2“ – 11 1/2 NPT 2.209 60.092 55.00 11.5
2 1/2“ – 8 NPT 3.175 72.699 65.50 8
3“ – 8 NPT 3.175 88.608 81.50 8
3 1/2“ – 8 NPT 3.175 101.316 94.30 8
4“ – 8 NPT 3.175 113.973 107.00 8
5“ – 8 NPT 3.175 141.300 134.384 8
6“ – 8 NPT 3.175 168.275 161.191 8
8“ – 8 NPT 3.175 219.075 211.673 8
10“ – 8 NPT 3.175 273.050 265.311 8
12“ – 8 NPT 3.175 323.850 315.793 8
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