NF A49-875-7-1996
钢管的无损检验.第7部分:纵向缺陷探测用无缝钢管和焊接(除埋弧焊外)钢管的自动全周边超声波试验
Non destructive testing of steel tubes. Part 7 : automatic full peripheral ultrasonic testing of seamless and welded (except submerged arc welded) steel tubes for the detection of longitudinal imperfections.