We recieved some 14" elbows sch.40 that were stamped WPB but the A234 was not included in the markings. I do not have the ASTM standard for pipe markings MSS-SP-25 so it is hard to look up this info. Is A234 a standalone for WPB or can anyone tell me if the A234 has to be stamped on the pipe. I appreciate any info on this topic. Dan