M——粗牙普通螺纹 MF——普通单牙细螺纹 PG——德国DIN40430标准螺纹 (German standard thread conforming to DIN40430) NPT——美国标准一般用途锥管螺纹(旧代号Z;K)Taper pipe thread for general purpose ( Old thread code Z,K ) UNC——美国标准统一制粗牙螺纹(代替NC)Unified coarse pitch thread ( Instead of NC) UNF——美国标准统一制细牙螺纹(代替NF)Unified fine pitch thread ( Instead of NF) BSW——英国标准惠氏螺纹(粗牙)British Standard Whitworth Thread ( Coarse)本回答被提问者采纳