6-8 NPT vs 3/4"-11.5NH: 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 26.99 mm.
| Spec | 6-8 NPT | 3/4"-11.5NH |
|---|---|---|
| Designation | 6-8 NPT | 3/4"-11.5NH |
| Major diameter | 168.27 mm | 26.99 mm |
| Threads per inch / pitch | 8 | 11.5 |
| Thread form | tapered, 60 degree | straight (parallel), 60 degree |
| Seals on | on the thread flanks with PTFE tape | flat washer or O-ring in the female coupling |
Questions and answers
Which has the higher major diameter, 6-8 NPT or 3/4"-11.5NH?
On major diameter, 6-8 NPT leads: 168.27 mm versus 26.99 mm.
How do 6-8 NPT and 3/4"-11.5NH compare?
On major diameter, 6-8 NPT leads: 168.27 mm versus 26.99 mm.