1
For 1, thread standard is NPT; threads per inch (tpi) is 11 1/2; thread pitch (mm) is 2.2087; major (outside) diameter (mm) is 33.4010; thread angle (degrees) is 60, recorded from its source on 2026-08-12.
- Thread standard
- NPT our reading
- Nominal size
- 1 verified
- Threads per inch (TPI)
- 11 1/2
- Thread pitch (mm)
- 2.2087
- Major (outside) diameter (mm)
- 33.4010 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
1.315 | 33.4010 |
— 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.
Threads per inch (TPI)
en.wikipedia.org says threads per inch (tpi) is 11 1/2, as of 2026-08-12.
1.315 | 33.4010 |
https://en.wikipedia.org/wiki/National_pipe_thread
trimantec.com says threads per inch (tpi) is 11½, as of 2026-08-12.
-16 (1) | 11½ | 33.3 | 1.31 | 31.5 | 1.24
https://trimantec.com/blogs/t/thread-identification-guide
Major (outside) diameter (mm)
en.wikipedia.org says major (outside) diameter (mm) is 33.4010, as of 2026-08-12.
1.315 | 33.4010 |
https://en.wikipedia.org/wiki/National_pipe_thread
trimantec.com says major (outside) diameter (mm) is 33.3, as of 2026-08-12.
-16 (1) | 11½ | 33.3 | 1.31 | 31.5 | 1.24
Sources
- en.wikipedia.orghttps://en.wikipedia.org/wiki/National_pipe_thread
- trimantec.comhttps://trimantec.com/blogs/t/thread-identification-guide