# 2 — Plumbing fitting and pipe thread standards

For 2, thread standard is BSP; threads per inch (tpi) is 11; thread pitch (mm) is 2.309; major (outside) diameter (mm) is 59.614; minor diameter (mm) is 56.656, recorded from its source on 2026-08-12.

- **Thread standard:** BSP _(our reading, not quoted from the source)_
- **Nominal size:** 2 _(verified: appears in the quote below)_
- **Threads per inch (TPI):** 11 _(verified: appears in the quote below)_
- **Thread pitch (mm):** 2.309 _(verified: appears in the quote below)_
- **Major (outside) diameter (mm):** 59.614 _(verified: appears in the quote below)_
- **Minor diameter (mm):** 56.656 _(verified: appears in the quote below)_
- **Thread angle (degrees):** 55 _(our reading, not quoted from the source)_
- **Governing standard:** ISO 228-1 _(our reading, not quoted from the source)_

## What the source says

> 2 | 11 | 2.309 | 1.479 | 59.614 | 58.135 | 56.656 |

## 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.

### Major (outside) diameter (mm)

amesweb.info says major (outside) diameter (mm) is **59.614**, as of 2026-08-12.

> 2 | 11 | 2.309 | 1.479 | 59.614 | 58.135 | 56.656 |

Source: https://amesweb.info/Screws/BSP-Thread-Chart.aspx

htsspares.com says major (outside) diameter (mm) is **59.61**, as of 2026-08-12.

> 2 Inch BSP | 59.61 mm / 2-1/4" | 11

Source: https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings

trimantec.com says major (outside) diameter (mm) is **59.7**, as of 2026-08-12.

> -32 (2) | 11 | 59.7 | 2.35 | 57.4 | 2.26

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


## Source

- https://amesweb.info/Screws/BSP-Thread-Chart.aspx
- https://www.htsspares.com/blog/how-to/how-to-measure-your-bsp-fittings
- 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/).