Question

what's the angle of NPT and BSP thread ?

Answer 1

Hello friend here is your answer.
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BSPT Connections. BSPT (British Standard Pipe Thread) is similar to NPT except for one important difference. The angle across the flanks of threads (if you sliced the fitting in half long-ways and measured the angle from root to crest to root) is 55 degreesinstead of 60 degrees as it is for NPT.
i hope it will help you