螺纹代号 基本尺寸 大径 mm d=D 螺距mmp 每英寸牙数tpi 中径mm d2=D2小径外螺纹d3 牙型高度 H1 底孔尺寸 mm G 1/8 1/8" 9.728 0.90728 9.1478.5660.581 8.7 G 1/4 1/4" 13.157 1.33719 12.301 11.4450.856 11.6 G 3/8 3/8" 16.662 1.33719 15.80614.950.856 15 G 1/2 1/2" 20.955 1.81414 19.793 18.6311.162 19 G 5/8 5/8" 22.911 1.81414 21.749 20.5871.162 20.75 G 3/4 3/4" 26.441 1.81414 25.279 24.1171.162 24.5 G 7/8 7/8" 30.201 1.81414 29.039 27.8771.162 28 G 1 1" 33.249 2.30911 31.7730.2911.479 30.5 G 1 1/8 1 1/8" 37.897 2.30911 36.418 34.9391.479 35 G 1 1/4 1 1/4" 41.91 2.30911 40.431 38.9521.479 39.5 G 1 3/8 1 3/8" 44.323 2.30911 42.844 41.3651.479 41.5 G 1 1/2 1 1/2" 47.803 2.30911 46.324 44.8451.479 45 G 1 3/4 1 3/4" 53.746 2.30911 52.267 50.7881.479 51 G 2 2" 59.614 2.30911 58.135 56.6561.479 57 G 2 1/4 2 1/4" 65.71 2.30911 64.231 62.7521.479 63 G 2 1/2 2 1/2" 75.184 2.30911 73.705 72.2261.479 72.5 G 2 3/4 2 3/4" 81.534 2.30911 80.055 78.5761.479 79 G 3 3" 87.884 2.30911 86.405 84.9261.479 85.5 G 3 1/4 3 1/4" 93.98 2.30911 92.501 91.