Different thread sealing depending on the geographical region,size of the pressure system and the environment. Fox example, In Asia, such as China, Korea, Japan etc normally use BSPT; In U.S, Canada etc always use NPT, then for BSPP thread most popular in UK, Europe, Australia, New Zealand and South Africa. While one sealing style is not inherently better than another each style has its application.
NPT Connections ( National Pipe Thread)- US & Canada
It is according to ANSI/ASME B1.20.1 Pipe Threads. 60 degree of thread angle. NPT male adapters have a taper thread that wedges into the female NPT adapter.
BSPT Connections (British Standard Pipe Taper)- China, Korea, Japan
BSPT thread is similar to NPT except for one important difference. The angle across the flanks of threads is 55 degrees instead of 60 degree as it is for NPT thread. Thus an NPT male thread could fit into BSPT female thread, but couldn’t sealing.
BSPP Connections ( British Standard Pipe Parallel)- UK, Europe, Australia,South Africa
BSPP thread is also British standard. It is a parallel thread fitting that uses a bonded seal ring to do the sealing. For historical reasons, BSPP has other different names at the same time. Such as BSPF ( British standard pipe fitting), BSPM(British Standard Pipe Mechanical) and PS (British Standard Pipe Straight) and so on.
For our thread valves & thread fittings, thread standard always most important for manufacture.
So please pay more attention about these difference.
BSPT & BSPP both referred to as BSP, so most of our customer maybe only told you needs BSP thread. Normally for female thread, 99% is BSPP. For male thread, BSPT & BSPP, 50%.
1) BSPP male thread could 100% connected with BSPP female thread,but NOT MATCH BSPT Female Thread
2) BSPT male thread couldn't 100% connected with BSPP female thread, needs using PTFE tap.