In the "Buyer Beware" category:
One type of item that I have gotten burned on at Amazon recently is NPT plumbing fittings. The vast majority of the advertised "NPT" products recently have all been metric G threads, aka BSPP/BSPT, which are the same diameter and thread pitch as NPT, but they are a parallel pipe thread that needs an o-ring or washer to seal. So, threading BSPT into NPT doesn't get to an interference fit, resulting in gobs of sealant and tape, or leaks.
(BSPP= British Standard Parallel Pipe (Thread))
(BSPT= British Standard Pipe Tapered (different thread profile)
I was looking for an NPT cap/plug set last night, and every plug/cap that I found with a high resolution image was not actually NPT. Grrr...
All the best,
Peter
More here for the curious;
Pressure systems in the process industry use different ways of sealing depending on the geographical region, size of the pressure system, and…
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