英制管螺纹基本尺寸及公差（牙形角55o）BSPP螺纹代号基本直径内螺纹外螺纹大径中径小径中径公差小径公差A 级B 级中径公差大径公差中径公差大径公差G1/8″ × 28 9.728 9.147 8.566 +0.170 +0.282 0 0 -0.107 0 -0.214 0 -0.214 0 -0.214 G1/4″ × 19 13.157 12.301 11.445 +0.125 +0.445 -0.125 -0.250 -0.250 0-0.250 G3/8″ × 19 16.662 15.806 14.950 +0.125 0 +0.445 0 0 -0.125 0 -0.250 0 -0.250 0 -0.250 G1/2″ × 14 20.955 19.793 18.631 +0.142 0 +0.541 0 0 -0.142 0 -0.284 0 -0.284 0 -0.284 G5/8″ × 14 22.911 21.749 20.587 +0.142 0 +0.541 0 0 -0.142 0 -0.284 0 -0.284 0 -0.284 G3/4″ × 14 26.441 25.279 24.117 +0.142 0 +0.541 0 0 -0.142 0 -0.284 0 -0.284 0 -0.284 G1″ × 11 33.249 31.770 30.291 +0.180 0 +0.640 0 0 -0.180 0 -0.360 0 -0.360 0 -0.360 G1.1/4″ × 11 41.910 40.431 38.952 +0.180 0 +0.640 0 0 -0.180 0 -0.360 0 -0.360 0 -0.360 G1.1/2″ × 11 47.803 46.324 44.854 +0.180 0 +0.640 0 0 -0.180 0 -0.360 0 -0.360 0 -0.360 G2″ × 11 59.614 58.135 56.656 +0.180 0 +0.640 0 0 -0.180 0 -0.360 0 -0.360 0 -0.360 G2.1/2 ” X1175.184 73.705 72.226 +0.217 0 +0.640 0 0 -0.217 0 -0.434 0 -0.434 0 -0.434 G3” X1187.884 86.405 84.926 +0.217 0 +0.640 0 0 -0.217 0 -0.434 0 -0.434 0 -0.434 G3.1/2 ” X11100.330 98.851 97.372 +0.217 0 +0.640 0 0 -0.217 0 -0.434 0 -0.434 0 -0.434 英制锥管螺纹基本尺寸及公差（牙形角55o）BSPT螺纹代号基面上的直径基准长度有效螺纹长度圆锥内螺纹基面轴向位移偏差（ ±mm）大径中径小径基本最大最小基本最大最小R1/8″ × 28 9.728 9.147 8.566 4.0 4.9 3.1 6.5 7.4 5.6 1.1 R1/4″ × 19 13.157 12.301 11.445 6.0 7.3 4.7 9.7 11.0 8.4 1.7 R3/8″ × 19 16.662 15.806 14.950 6.4 7.7 5.1 10.1 11.4 8.8 1.7 R1/2″ × 14 20.955 19.793 18.631 8.2 10.0 6.4 13.2 15.0 11.4 2.3 R3/4″ × 14 26.441 25.279 24.117 9.5 11.3 7...
