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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°)
1> BSW－－－－英国标准惠氏螺纹（粗牙）British Standard Whitworth Thread
( Coarse )
2> BSF－－－－英国标准惠氏螺纹（细牙）British Standard Whitworth Thread
( Fine )
3> 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 A\\B: taps in G、G－D )
4> R－－－－锥管外螺纹（旧代号ZG;KG）Outside paper pipe thread ( Old
thread code ZG,KG )
5> 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 60°
1> UNC－－－－统一制粗牙螺纹（代替NC）Unified coarse pitch thread ( Instead
of NC )
2> UNF－－－－统一制细牙螺纹（代替NF）Unified fine pitch thread ( Instead of
NF )
3> UNEF－－－－统一制超细牙螺纹Unified superfine pitch thread 4> UN－－－－－统一制不变螺距螺纹Unified thread 5> UNS－－－－统一制特殊螺纹Unified Special thread
6> NPT－－－－一般用途锥管螺纹（旧代号Z;K）Taper pipe thread for general
purpose ( Old thread code Z,K )
7> NPSC－－－－管接头直管内螺纹Internal straight pipe thread for connection 8> NPSM－－－－设备上自由配合，机械连接用直管螺纹Straight pipe thread
for general purpose
9> NPTF－－－－干密封锥管螺纹Dryseal taper pipe thread
10> NPSF－－－－干密封燃油直管螺纹Dryseal straight pipe internal thread
11> NGT－－－－气瓶用锥螺纹Special thread for gas cylinder 三、米制螺纹Metric thread
ZM－－－－－米制锥管螺纹 Metric taper pipe thread 四、其它螺纹Other threads
SM－－－－缝纫机螺纹Thread for sewing machine PZ－－－－气瓶用锥螺纹Special thread for gas cylinder 5V1－20V1－气门芯螺纹5V1－20V1－Tyre valve thread
螺纹代号说明示例：Explanation of thread code. e. g. 1/4－20UNC
1/4－公称直径1/4\ 20－每寸20牙twenty teeth per inch
UNC－美标统一制粗牙螺纹unified coarse pitch thread ( American standard)