螺纹底孔对照表(更新版)普通牙螺纹孔公称尺寸M2M2.5M3M4M5M6M8M10M12M14M16M18M20M24M27M30M33M36M42M48M52M56M64底孔1.0牙距(D)公称尺寸1.622.53.34.256.88.510.2121415.517.5212426.529.53237.5434750.558平行管内螺纹Rp1/16Rp1/2Rp1/4Rp3/4Rp1/8Rp3/86.52411.414.98.514.9R------英制一般密封管螺纹Rc-----英制密封圆锥内螺纹Rp-----英制密封圆柱内螺纹G------英制非密封管螺纹M8M10M12M14M16M18M20M22M24M27M30普通细牙螺纹孔底孔1.5牙距(D)公称尺寸79111315171921232629M12M14M16M18M20M22M24M27M30M33M36M42M48底孔(D)10.512.514.516.518.520.522.525.528.531.534.540.546.5底孔公称尺寸(D)M20M22M24M27M30M33M36M42M48M52182022252831344046502.0牙距中国（旧）ZG1/8″ZG1/4″ZG3/8″ZG1/2″ZG3/4″ZG1″ZG1 1/4″ZG1 1/2″ZG2″ZG2 1/2″ZG3″圆锥管螺纹孔（55°）公称尺寸中国（新）Rc1/8″Rc1/4″Rc3/8″Rc1/2″Rc3/4″Rc1″Rc1 1/4″Rc1 1/2″Rc2″Rc2 1/2″Rc3″日本PT1/8″PT1/4″PT3/8″PT1/2″PT3/4″PT1″PT1 1/4″PT1 1/2″PT2″PT2 1/2″PT3″底孔(D)8.41114.51823.529.53844567284圆柱管螺纹孔（55°）公称尺寸G1/8″G1/4″G3/8″G1/2″G3/4″G1″G1 1/8″G1 1/4″G1 1/2″G1 3/4″G2″G2 1/4″G2 1/2″G2 3/4″G3″底孔(D)8.611.715.218.824.330.535.239.245.15156.962.9572.4578.885.2布锥管螺纹孔（60°）公称尺寸中国（旧）Z1/8″Z1/4″Z3/8″Z1/2″Z3/4″Z1″Z1 1/4″Z1 1/2″Z2″中国（新）NPT1/8″NPT1/4″NPT3/8″NPT1/2″NPT3/4″NPT1″NPT1 1/4″NPT1 1/2″NPT2″底孔(D)8.411.114.618.123.529.438.244.356.3