# 2 — Plumbing fitting and pipe thread standards

For 2, thread standard is NPT; threads per inch (tpi) is 11 1/2; thread pitch (mm) is 2.2087; major (outside) diameter (mm) is 60.3250; thread angle (degrees) is 60, recorded from its source on 2026-08-12.

- **Thread standard:** NPT _(our reading, not quoted from the source)_
- **Nominal size:** 2 _(verified: appears in the quote below)_
- **Threads per inch (TPI):** 11 1/2
- **Thread pitch (mm):** 2.2087
- **Major (outside) diameter (mm):** 60.3250 _(verified: appears in the quote below)_
- **Thread angle (degrees):** 60 _(our reading, not quoted from the source)_
- **Governing standard:** ASME B1.20.1 _(our reading, not quoted from the source)_

## What the source says

> 2.375 | 60.3250 |

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Threads per inch (TPI)

en.wikipedia.org says threads per inch (tpi) is **11 1/2**, as of 2026-08-12.

> 2.375 | 60.3250 |

Source: https://en.wikipedia.org/wiki/National_pipe_thread

geminivalve.com says threads per inch (tpi) is **11½**, as of 2026-08-12.

> 2 | 11½ | 0.08696 | 2.20878 | 2.375 | 60.33

Source: https://www.geminivalve.com/bsp-thread-vs-npt-fitting/

trimantec.com says threads per inch (tpi) is **11½**, as of 2026-08-12.

> -32 (2) | 11½ | 60.4 | 2.38 | 57.9 | 2.29

Source: https://trimantec.com/blogs/t/thread-identification-guide


### Thread pitch (mm)

en.wikipedia.org says thread pitch (mm) is **2.2087**, as of 2026-08-12.

> 2.375 | 60.3250 |

Source: https://en.wikipedia.org/wiki/National_pipe_thread

geminivalve.com says thread pitch (mm) is **2.20878**, as of 2026-08-12.

> 2 | 11½ | 0.08696 | 2.20878 | 2.375 | 60.33

Source: https://www.geminivalve.com/bsp-thread-vs-npt-fitting/


### Major (outside) diameter (mm)

en.wikipedia.org says major (outside) diameter (mm) is **60.3250**, as of 2026-08-12.

> 2.375 | 60.3250 |

Source: https://en.wikipedia.org/wiki/National_pipe_thread

geminivalve.com says major (outside) diameter (mm) is **60.33**, as of 2026-08-12.

> 2 | 11½ | 0.08696 | 2.20878 | 2.375 | 60.33

Source: https://www.geminivalve.com/bsp-thread-vs-npt-fitting/

trimantec.com says major (outside) diameter (mm) is **60.4**, as of 2026-08-12.

> -32 (2) | 11½ | 60.4 | 2.38 | 57.9 | 2.29

Source: https://trimantec.com/blogs/t/thread-identification-guide


## Source

- https://en.wikipedia.org/wiki/National_pipe_thread
- https://www.geminivalve.com/bsp-thread-vs-npt-fitting/
- https://trimantec.com/blogs/t/thread-identification-guide

Last verified: 2026-08-12. Review by: 2028-08-11.
Part of [Plumbing fitting and pipe thread standards](https://referencesource.org/plumbing-fitting-thread-standards/).