British Standard Pipe Designations:

BSP = British Standard Pipe. This designation can be used to broadly define either Brutish Standard Pipe Taper or British Standard Pipe Parallel which leaves a question as to which of the two is actually designated. It is best to avoid this designation at all times. more

BSPF = British Standard Pipe Fitting is an obsolete designation which has been replaced with the G-Series.

BSPM = British Standard Pipe Mechanical is an obsolete designation which has been replaced with the G-Series.

BSPP = British Standard Pipe Parallel is an obsolete designation still in common usage and has been officially replaced with the G-Series.

BSPT = British Standard Pipe Taper is an obsolete designation still in common usage which has been replaced with the R-Series

R = External tapered screw pipe thread for fits made on the thread per ISO-7 & BS-21. Per the standard the R mates with the Rc and Rp, but will also mate with the G.

Rc = internal tapered threads for fits made on the thread per ISO-7 & BS-21. Per the standard Rc mates with R.
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Rp = internal parallel thread for fits made on the thread per ISO-7 & BS-21. Per the standard Rp mates with R.

Rs = external parallel thread for fits made on machined face per BS-21 Appendix C.

G = internal or external threads for fits where seal is not on the thread per ISO-228 & obsolete BS-2779. G series is designed to mate with G series.

Comments about the above statement can be sent to: gageguy@gagecrib.com