NPSC Pipe Thread ANSI B 1.20.1-1983 (R1992)

The parallel pipe thread National Pipe Straight Coupling is combined with the tapered fitting threa National Pipe Taper using a sealant. The flank angle is 60°, the profile was originated by William Sellers.

Nominal Diameter Major Diameter
mm
Major Diameter
Inch
Tapping
Drill Size
mm
TPI Pitch
mm
1/8" - 27 NPSC 10.034 0.395 8.636 27 0.941
1/4" - 18 NPSC 13.329 0.525 11.227 18 1.411
3/8" - 18 NPSC 16.768 0.660 14.656 18 1.411
1/2" - 14 NPSC 20.888 0.822 18.161 14 1.814
3/4" - 14 NPSC 26.235 1.033 23.495 14 1.814
1" - 11 1/2 NPSC 32.848 1.293 29.489 11.5 2.209
1 1/4" - 11 1/2 NPSC 41.603 1.638 38.252 11.5 2.209
1 1/2" - 11 1/2 NPSC 47.674 1.877 44.323 11.5 2.209
2" - 11 1/2 NPSC 59.711 2.351 56.363 11.5 2.209
2 1/2" - 8 NPSC 72.214 2.843 67.310 8 3.175
3" - 8 NPSC 88.125 3.469 83.236 8 3.175
3 1/2" - 8 NPSC 100.832 4.970 95.936 8 3.175
4" - 8 NPSC 113.489 4.468 108.585 8 3.175