1/2
For 1/2, thread standard is NPT; threads per inch (tpi) is 14; thread pitch (mm) is 1.8143; major (outside) diameter (mm) is 21.3360; thread angle (degrees) is 60, recorded from its source on 2026-08-12.
- Thread standard
- NPT our reading
- Nominal size
- 1/2
- Threads per inch (TPI)
- 14
- Thread pitch (mm)
- 1.8143
- Major (outside) diameter (mm)
- 21.3360 verified
- Thread angle (degrees)
- 60 our reading
- Governing standard
- ASME B1.20.1 our reading
Values marked our reading are our classification of what the source says — the source does not print them in those words. The quote below is the evidence for each one; judge it yourself.
What the source says
0.840 | 21.3360 |
— en.wikipedia.org, retrieved 2026-08-12
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 — deciding between them is yours, not ours.
Thread pitch (mm)
en.wikipedia.org says thread pitch (mm) is 1.8143, as of 2026-08-12.
0.840 | 21.3360 |
https://en.wikipedia.org/wiki/National_pipe_thread
geminivalve.com says thread pitch (mm) is 1.81432, as of 2026-08-12.
1/2 | 14 | 0.07143 | 1.81432 | 0.84 | 21.34
https://www.geminivalve.com/bsp-thread-vs-npt-fitting/
Major (outside) diameter (mm)
en.wikipedia.org says major (outside) diameter (mm) is 21.3360, as of 2026-08-12.
0.840 | 21.3360 |
https://en.wikipedia.org/wiki/National_pipe_thread
geminivalve.com says major (outside) diameter (mm) is 21.34, as of 2026-08-12.
1/2 | 14 | 0.07143 | 1.81432 | 0.84 | 21.34
https://www.geminivalve.com/bsp-thread-vs-npt-fitting/
trimantec.com says major (outside) diameter (mm) is 21.3, as of 2026-08-12.
-08 (1/2) | 14 | 21.3 | 0.84 | 19.3 | 0.76
Sources
- en.wikipedia.orghttps://en.wikipedia.org/wiki/National_pipe_thread
- geminivalve.comhttps://www.geminivalve.com/bsp-thread-vs-npt-fitting/
- trimantec.comhttps://trimantec.com/blogs/t/thread-identification-guide