British Standard Pipe Designations:

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

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.

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

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

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