gov spec requiring nitrogen purge while weld is being performed.gov spec ref's to ASME B31.1 and B31.9. Weld procedure QW-482 smaw, joint design vee,backing none,base metal (QW-403) P-# 1,,GRP # 1,Spec SA 106 GR-B,base metal .0625 to .436 all dia with in T range,,filler metals QW404,spec. no...