Both families include variants and require the exact designation. Visual inspection and hand engagement alone are not enough for a reliable pressure connection.
Name the exact variant
Distinguish tapered from parallel forms and identify the sealing method. NPT, NPTF, BSPT and BSPP are not interchangeable labels.
Why a fitting can appear to fit
A few turns of engagement can occur between mismatched systems, but flank form, pitch, diameter and sealing behavior can still be wrong. Forcing the connection can damage both parts.
Important limitation
Pressure systems require applicable codes, rated components and qualified procedures. This identification overview is not a pressure-design instruction.
Pressure systems require applicable codes, rated components and qualified procedures. This identification overview is not a pressure-design instruction.
Technical references
- ASME B1.20.1-2013 (R2018) Pipe Threads, General Purpose, Inch — ASME. Accessed 2026-11-10.
Standards references identify scope and terminology; protected dimensional tables are not reproduced.