1、 螺纹代号 Thread Code一、英制螺纹（螺纹牙型角 55 度）Thread of British standard ( Thread pitch shape angle 55)BSW英国标准惠氏螺纹（粗牙）British Standard Whitworth Thread ( Coarse )BSF英国标准惠氏螺纹（细牙）British Standard Whitworth Thread ( Fine )G直管螺纹（外螺纹分 A、B 两面级、丝锥分 G、G D ）Straight pipe thread ( Outside ) thread in AB: taps in G、G D )
2、R锥管外螺纹（旧代号 ZG;KG）Outside paper pipe thread ( Old thread code ZG,KG )RC锥管内螺纹（旧代号 ZG;KG）Inside taper pipe thread ( Old thread code ZG,KG )二、美制螺纹（螺纹牙型角 60 度）Thread of American standard ( Thread pitch shape angle 60UNC统一制粗牙螺纹（代替 NC）Unified coarse pitch thread ( Instead of NC )UNF统一制细牙螺纹（代替 NF）Unified fi
3、ne pitch thread ( Instead of NF )UNEF统一制超细牙螺纹 Unified superfine pitch threadUN统一制不变螺距螺纹 Unified threadUNS统一制特殊螺纹 Unified Special threadNPT一般用途锥管螺纹（旧代号 Z;K）Taper pipe thread for general purpose ( Old thread code Z,K )NPSC管接头直管内螺纹 Internal straight pipe thread for connectionNPSM设备上自由配合，机械连接用直管螺纹 Strai
4、ght pipe thread for general purposeNPTF干密封锥管螺纹 Dryseal taper pipe threadNPSF干密封燃油直管螺纹 Dryseal straight pipe internal threadNGT气瓶用锥螺纹 Special thread for gas cylinder三、米制螺纹 Metric threadZM米制锥管螺纹 Metric taper pipe thread四、其它螺纹 Other threadsSM缝纫机螺纹 Thread for sewing machinePZ气瓶用锥螺纹 Special thread for gas cylinder5V120V1气门芯螺纹 5V120V1Tyre valve thread螺纹代号说明示例：Explanation of thread code. e. g.1/420UNC1/4公称直径 1/4“ nominal dia. 1/4“20每寸 20 牙 twenty teeth per inchUNC美标统一制粗牙螺纹 unified coarse pitch thread ( American standard
