BSPF = British Standard Pipe Fitting is an obsolete designation which has been replaced with the G-Series per ISO 228 BSPF was the thread marking per screw thread designation BS-2779. BS-2779 has been rescinded and should no longer be used. The new screw thread designation is specifies a G in front of the nominal diameter and is defined in ISO-228. In March 2003, the British Standards Institute withdrew BS-2779 and replaced it with ISO-228 (technically BS-EN-ISO-228) Example: G1/2 x 14 BSPP Go Thread Ring Gage - Class A Class A is considered the standard tolerance. Class B is a loose tolerance twice the amount of Class A. Class B only refers to the No Go Thread Ring Gage There are many drawings that call out British Standard Pipe (BSP) to refer the current G-series screw thread. It should always be confirmed as BSP may also be a shortened version of BSPT -British Standard Pipe Taper. For more information on British Pipe Threads and British Standard Pipe Fitting,  you may contact [email protected] or visit our website https://www.threadcheck.com