Getting to Leakproof with NPT & NPTF Threads: What Matters
https://www.industrialspec.com/about-us/blog/detail/npt-nptf-tapered-threads-and-leakproof-seals
NPT and NPTF threads will screw together, but they do differ slightly in the diameter of their thread crests (major diameter) and thread roots (minor diameter), as well as their allowed tolerances. While NPTF thread crests have the same shape and major diameter as NPT, their tolerance range is narrower and more carefully controlled.
DA: 61 PA: 18 MOZ Rank: 37