What is the difference between BSP and BSPT thread?

This one is quite simple, a BSP thread is British Standard Pipe and BSPT thread is British Standard Pipe Tapered. You will note our earlier blog about how to measure a BSP thread, which is extracted as below. 

  • A 3/8 Inch BSP thread measures approximately 5/8 inch in diameter
  • A 1/2 Inch BSP thread measures approximately 3/4 inch in diameter
  • A 3/4 Inch BSP thread measures approximately 1 inch in diameter
  • A 1 Inch BSP thread measures approximately 1 1/4 inches in diameter
  • A 1 1/4 Inch BSP thread measures approximately 1 1/2 inches in diameter
  • A 1 1/2 Inch BSP thread measures approximately 1 3/4 inches in diameter.....etc

Essentially this is the same measurement rule for BSPT threads, the only difference is how the thread seals. On a BSP or parallel thread a fibre or rubber washer (and/or jointing compound if required) should be used on the male thread and then screwed into the female BSP thread until the shoulders of the male and female meet and then the seal is made by the washers. On a BSPT tapered thread there are no shoulders to seal with a washer. The male thread should be wrapped several times around with PTFE jointing tape (and/or jointing compound) and then the male screwed into the female. As the threads are tapered they will get tighter and tighter until it is very difficult to screw further. The seal is therefore made with the tape and sealant

A helpful tip is to wrap PTFE tape around the male threads in a clockwise direction so that when the thread is screwed in it does not unravel the PTFE off the thread. Our extensive range of BSP male and female adapters can be found here

19th Oct 2020

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