1、 NPT：美国标准的 60 度锥管螺纹美制一般密封管螺纹的基本尺寸： 基准平面内的基本直径 螺距P牙型高度h大径d=D中径d1=D2小径d1=D1基准距离 L1 装配余 量 L3外螺纹小端面内的基本小径 尺寸代号 牙数nmm 圈数 mm 圈数 mm mm1/16 27 0.9410.752 7.894 7.142 6.389 4.32 4.064 3 2.822 6.1371/8 27 0.9410.752 10.242 9.489 8.737 4.36 4.102 3 2.822 8.4811/4 18 1.4111.129 13.616 12.487 11.358 4.10 5.785 3
2、 4.233 10.9963/8 18 1.4111.129 17.055 15.926 14.797 4.32 6.096 3 4.233 14.4171/2 14 1.8141.451 21.224 19.772 18.321 4.48 8.128 3 5.443 17.8133/4 14 1.8141.451 26.569 25.117 23.666 4.75 8.618 3 5.443 23.1271 11.52.2091.767 33.228 31.461 29.694 4.60 10.160 3 6.626 29.06011/4 11.52.2091.767 41.985 40.2
3、18 38.451 4.83 10.668 3 6.350 37.78811/2 11.52.2091.767 48.054 46.287 44.520 4.83 10.668 3 6.350 43.8532 11.52.2091.767 60.092 58.325 56.558 5.01 11.065 3 6.350 55.86721/2 8 3.1752.540 72.699 70.159 67.619 5.46 17.335 2 6.350 66.5353 8 3.1752.540 88.608 86.068 83.528 6.13 19.463 2 6.350 62.31131/2 8
4、 3.1752.540101.316 98.776 96.236 6.57 20.860 2 6.350 94.9324 8 3.1752.540113.973111.433108.893 6.75 21.431 2 6.350107.5545 8 3.1752.540140.952138.412135.872 7.50 23.812 2 6.350134.3846 8 3.1752.540167.792165.252162.712 7.66 24.320 2 6.350161.1918 8 3.1752.540218.441215.901213.361 8.50 26.988 2 6.350
5、211.67310 8 3.1752.540272.312269.772267.232 9.68 30.734 2 6.350265.31112 8 3.1752.540323.032320.492317.95210.8834.544 2 6.350315.79314O.D. 8 3.1752.540354.904352.364349.82412.5039.688 2 6.350347.34516O.D. 8 3.1752.540405.784403.244400.70414.5046.038 2 6.350397.82818O.D. 8 3.1752.540456.565454.025451
6、.48516.0050.800 2 6.350448.31020O.D. 8 3.1752.540507.246504.706502.16617.0053.975 2 6.350498.79224O.D. 8 3.1752.540608.608606.068603.52819.0060.325 2 6.350599.758注： 可参考表中的最右边一列数据选择攻丝前的麻花钻直径； 螺纹收尾长度（V）为 3.47 P； O.D.是英文管子外径（outside diameter）的缩写。 标记：美制一般密封管螺纹的完整标记由螺纹特征代号，螺纹尺寸代号和旋向代号组成。左旋螺纹的旋向代号为 LH；右旋螺纹的旋向代号省略不标。例如： 1/8 NPT-LH,1/8 表示螺纹尺寸，NPT 为螺纹特征代号，LH 表示左旋。美制管螺纹的米制化方法：将管螺纹的原英寸尺寸乘以 25.4 就转化为毫米尺寸。
