R1-1/2 vs 1-1/2-11.5 NPT: specs compared
Updated 05 September 2026.
48.26 mm
1-1/2-11.5 NPT wins on major diameter
On major diameter, 1-1/2-11.5 NPT leads: 48.26 mm versus 47.803 mm.
| Spec | R1-1/2 | 1-1/2-11.5 NPT |
|---|---|---|
| Designation | R1-1/2 | 1-1/2-11.5 NPT |
| Major diameter | 47.803 mm | 48.26 mm |
| Threads per inch / pitch | 11 | 11.5 |
| Thread form | tapered, 55 degree | tapered, 60 degree |
| Seals on | on the thread flanks with PTFE tape or paste | on the thread flanks with PTFE tape |
Questions and answers
Which has the higher major diameter, R1-1/2 or 1-1/2-11.5 NPT?
On major diameter, 1-1/2-11.5 NPT leads: 48.26 mm versus 47.803 mm.
How do R1-1/2 and 1-1/2-11.5 NPT compare?
On major diameter, 1-1/2-11.5 NPT leads: 48.26 mm versus 47.803 mm.