大径（基准
直径）d=D
中径d 2=D 2小径d 1=D 1
1/16280.9070.5810.1257.7237.142 6.5614
6.51/8280.9070.5810.1259.7289.1478.5664 6.5DN81/419 1.3370.5860.18413.15712.30111.44569.73/819 1.3370.5860.18416.66215.80614.950610.1DN151/221.3 2.8 2.4514 1.814 1.1620.24920.95519.79318.631813.2DN203/426.9 2.8 2.4514 1.814 1.1620.24926.44125.27924.1171014.5DN25133.7 3.2 2.811 2.309 1.4790.31733.24931.77030.2911016.8DN32 1.1/442.4 3.5 3.0611 2.309 1.4790.31741.91040.43138.9521319.1DN40 1.1/248.3 3.5 3.0611 2.309 1.4790.3174
7.80346.32444.8451319.1DN50260.3 3.8 3.32511 2.309 1.4790.31759.6145
8.13556.6561623.4DN65 2.1/276.14 3.5
11 2.309 1.4790.31775.18473.70572.2261826.7DN80388.9411 2.309 1.4790.31787.88486.40584.9262129.83.1/211 2.309 1.4790.317100.33098.85197.3722231.4DN1004114.3411 2.309 1.4790.317113.030111.551110.0722535.8DN1255140 4.511 2.309 1.4790.317138.430136.951135.4722940.1DN1506168.3 4.5
11
2.309
1.4790.317163.83016
2.351160.872
29
40.1
DN2008
219.1
DN250
大径（基准
直径）d=D
中径d 2=D 2小径d 1=D 1
1/16277.8957.142 6.389 4.064
1/82710.2429.4898.736 4.1021/41813.61612.48711.358 5.7863/81817.05515.92614.797 6.0961/21421.22319.77218.3218.1283/41426.56825.11723.6668.61111233.22831.46129.69410.1601.1/41241.98540.21838.45110.6681.1/21248.05446.28744.52010.66821260.09258.32556.55811.0742.1/2872.69970.15967.61917.3233888.60886.06883.52819.4563.1/28101.31698.77696.23620.8534
8113.973111.433108.893
21.438
1英寸=25.4mm=8分 以上壁厚尺寸以焊管、镀锌管理论重量为例（按GB/T3091-2001标准执行）
锥管螺纹的基本尺寸表（3-28）1/2PT 、1/2NPT 、
表（3-28）螺纹基本尺寸 (单位:mm)
尺寸代号每25.4mm
类的牙数n 基面上的基本直径
基准距离圆弧半径r ≈基面上的基本直径
基准距离有效螺纹长
度
最小壁厚
每25.4mm 类的牙数n
螺距p 牙型高度h 对应口径
尺寸代号外径
壁厚
通称尺寸
1分2分2寸2.5寸3分4分6分1寸6寸8寸10寸
管螺纹的基本尺寸表（3-29）G1/2 、ZG1/2 、（以焊管、镀锌管为例）
3寸3.5寸4寸5寸1.2寸1.5寸
