| Thread | American conical pipe thread acc. ANSI/ASME B 1.20.1 – 1983 |
| Abbreviation | NPT |
| Designation | 3/8 – 18 NPT |
| Type of thread | inside thread conical outside thread conical (cone 1:16) |
| Application | Pipe threads for pipes and tube connections with sealing tapes (see pages 8 – 10) are sealing inside the threads |
| Description | The conical NPT-outside thread shows at the relating level &147;. The adjustment power created by using of a suitable tool increases the thread reach and seals the screw connection supported by a suitable sealant (e.g. hemp or Teflon). Since both inside and outside threads are conical, more thread-turns contribute to better sealing and power admission. The little thread-flattening causes a small leakage space. |
thread | outside Ø of pipe | number of threads | P | h | effective Ø E1 | L1 | i |
|---|---|---|---|---|---|---|---|
| 1/8" NPT | 10.287 | 27 | 0.941 | 0.753 | 9.489 | 4.102 | 6.703 |
| 1/4" NPT | 13.761 | 18 | 1.411 | 1.129 | 12.487 | 5.786 | 10.206 |
| 3/8" NPT | 17.145 | 18 | 1.411 | 1.129 | 15.926 | 6.096 | 10.358 |
| 1/2" NPT | 21.336 | 14 | 1.814 | 1.451 | 19.772 | 8.128 | 13.556 |
| 3/4" NPT | 26.67 | 14 | 1.814 | 1.451 | 25.117 | 8.611 | 13.861 |
| 1" NPT | 33.401 | 11.5 | 2.209 | 1.767 | 31.461 | 10.16 | 17.343 |
| 1 1/4" NPT | 42.164 | 11.5 | 2.209 | 1.767 | 40.218 | 10.668 | 17.953 |
| 1 1/2" NPT | 48.26 | 11.5 | 2.209 | 1.767 | 46.287 | 10.668 | 18.377 |