BSP thread chart dimensions for pipe threads according to ISO 228 BSPP (parallel straight threads) and IS0 7 BSPT (taper threads). BSP thread uses Whitworth thread form with flank angle of 55 , All dimension are in millimetres. The letter symbols for pipe threads are as follows:
ISO 7 Standard (BSPT Thread):
- the letter R followed by the letter p for parallel internal threads;
- the letter R followed by the letter c for taper(conical) internal threads;
- the letter R for external threads;
ISO 228 Standard (BSPP Thread):
- the letter G for internal and external threads; (See ISO 228 BSPP (parallel straight threads) for more details)
1/4 BSP thread dimensions :
Thread pitch: 1.337 mm, Major Dia. : 13.157 mm, Pitch Dia.: 12.301 mm, Minor Dia.: 11.445 mm
1/2 BSP thread dimensions :
Thread pitch: 1.814 mm, Major Dia. :20.955 mm, Pitch Dia.: 19.793 mm, Minor Dia.: 18.631 mm
3/4 BSP thread dimensions :
Thread pitch: 1.814 mm, Major Dia. :26.441 mm, Pitch Dia.: 25.279 mm, Minor Dia.: 24.17 mm
1 BSP thread dimensions :
Thread pitch: 2.309 mm, Major Dia. :33.249 mm, Pitch Dia.: 31.770 mm, Minor Dia.: 30.291 mm
1 1/4 BSP thread dimensions :
Thread pitch: 2.309 mm, Major Dia. :41.910 mm, Pitch Dia.: 40.431 mm, Minor Dia.: 38.952 mm