无缝钢管的公称直径与外径之间的对照关系如下表所示（单位为毫米）：

| 公称直径 | 外径 |

| -------- | -------- |

| 6 | 10.2 |

| 8 | 13.7 |

| 10 | 17.1 |

| 15 | 21.3 |

| 20 | 26.9 |

| 25 | 33.7 |

| 32 | 42.4 |

| 40 | 48.3 |

| 50 | 60.3 |

| 65 | 76.1 |

| 80 | 88.9 |

| 90 | 101.6 |

| 100 | 114.3 |

| 125 | 141.3 |

| 150 | 168.3 |

| 200 | 219.1 |

| 250 | 273.0 |

| 300 | 323.9 |

| 350 | 355.6 |

| 400 | 406.4 |

| 450 | 457.0 |

| 500 | 508.0 |

| 550 | 559.0 |

| 600 | 610.0 |