6-8 NPT vs M22 x 1.5 (14 mm): specs compared
Updated 05 September 2026.
168.27 mm
6-8 NPT wins on major diameter
On major diameter, 6-8 NPT leads: 168.27 mm versus 22 mm.
| Spec | 6-8 NPT | M22 x 1.5 (14 mm) |
|---|---|---|
| Designation | 6-8 NPT | M22 x 1.5 (14 mm) |
| Major diameter | 168.27 mm | 22.0 mm |
| Threads per inch / pitch | 8 | 1.5 mm pitch |
| Thread form | tapered, 60 degree | parallel, metric |
| Seals on | on the thread flanks with PTFE tape | O-ring on the 14 mm spigot |
Questions and answers
Which has the higher major diameter, 6-8 NPT or M22 x 1.5 (14 mm)?
On major diameter, 6-8 NPT leads: 168.27 mm versus 22 mm.
How do 6-8 NPT and M22 x 1.5 (14 mm) compare?
On major diameter, 6-8 NPT leads: 168.27 mm versus 22 mm.