ANSI B1.20.1 - NPS - American National Standard Straight Pipe Threads
NPS pressure tight straight pipe threads with lubricant or sealer.
Dimensions of NPS - American National Standard Straight Pipe Thread - not self-sealing threads are indicated below:
| Pipe Size (inches) | TPI | Pipe Diameter (inches) | Female Thread Inside Diameter (inches) | Tap Drill |
|---|---|---|---|---|
| 1/8 | 27 | 0.405 | 0.34 | S |
| 1/4 | 18 | 0.540 | 0.47 | 29/64 |
| 3/8 | 18 | 0.675 | 0.59 | 19/32 |
| 1/2 | 14 | 0.840 | 0.75 | 47/64 |
| 3/4 | 14 | 1.050 | 0.97 | 15/16 |
| 1 | 11.5 | 1.315 | 1.20 | 1 3/16 |
| 1 1/4 | 11.5 | 1.660 | 1-55 | 1 33/64 |
| 1 1/2 | 11.5 | 1.900 | 1.79 | 1 3/4 |
| 2 | 11.5 | 2.375 | 2.26 | 2 7/32 |
| 2 1/2 | 8 | 2.875 | 2.71 | 2 21/32 |
| 3 | 8 | 3.500 | 3.33 | 3 9/32 |
| 3 1/2 | 8 | 4.000 | 3 25/32 | |
| 4 | 8 | 4.500 | 4 9/32 | |
| 4 1/2 | 8 | 5.000 | 4 25/32 | |
| 5 | 8 | 5.563 | 5 11/32 | |
| 6 | 8 | 6.625 | 6 13/32 |
- 1 inch = 25.4 mm
- TPI - Threads per Inch
- B1.20.1 Standard on Pipe Threads, General Purpose, Inch
Note that both NPT and NPS have the same thread angle, shape, and pitch (threads per inch). However, NPT threads are tapered and NPS threads are straight (parallel). Both threads have a 60° included angle and flat peaks and valleys.
