G3 vs 3-8 NPT: specs compared
Updated 05 September 2026.
88.9 mm
3-8 NPT wins on major diameter
On major diameter, 3-8 NPT leads: 88.9 mm versus 87.884 mm.
| Spec | G3 | 3-8 NPT |
|---|---|---|
| Designation | G3 | 3-8 NPT |
| Major diameter | 87.884 mm | 88.9 mm |
| Threads per inch / pitch | 11 | 8 |
| Thread form | parallel, 55 degree | tapered, 60 degree |
| Seals on | flat washer or bonded seal on the face | on the thread flanks with PTFE tape |
Questions and answers
Which has the higher major diameter, G3 or 3-8 NPT?
On major diameter, 3-8 NPT leads: 88.9 mm versus 87.884 mm.
How do G3 and 3-8 NPT compare?
On major diameter, 3-8 NPT leads: 88.9 mm versus 87.884 mm.