FlexPVC - What to do when they send you the wrong parts.

Another impromptu video, this time showing how a BSPP (British Standard Parallel Pipe) thread fit, but don't fit NPT threads. Actually a very important subject matter video since there is so much stuff coming out of China and India with a mixture of threads. And of course the correct solution to this problem.

[@larryseibold4287]

Good work posting this. You are spot on. I often forget about this issue. It is basically impossible to seal a tapered female NPT 1/2 or 3/4 threaded to a BSP straight male part (G1/2 or G3/4 @ 14TPI) without brazing or similar hardening sealer means, even though they both have the same basic diameters and TPI. What does work, and is becoming more popular is the point that you made in using face seals on either the tip or the base, ideally in a grove so that the rubber seal compression is limited by metal on metal contact. Note 1", 1/4" and 1/8" sizes are slightly different in TPI, but due to looseness will appear to go together, but are even more of an issue.
NPT/NPS and BSP threads are not compatible due to the differences in their thread forms, and not just the fact that most sizes have a different pitch. NPT/NPS threads have a 60° angle and have flattened peaks and valleys where as BSP threads have a 55° angle and have rounded peaks and valleys. Even if you laid on many wraps of lots of sealant, as the valley in the female part is never filed properly.
This issue is becoming more and more common as the world marches on but US seems incapable in joining the rest of the world in so many international standards due to legacy issues.