71.371.24271.90171.08871.52271.24471.3472.06571.76371.05971.0771.42971.03871.68771.13971.885
71.68671.05871.65671.46672.0871.7471.81971.8471.61271.0171.70171.01871.91671.65971.35971.683
71.98671.65171.80671.97971.76971.48871.67471.16571.57772.02771.48171.02371.58771.49871.17171.01
71.29571.671.77971.5871.52771.7671.07271.96971.47671.49171.35371.41971.56171.20271.72971.683
71.42871.49271.86171.88371.72671.49171.38872.07471.38771.1371.62771.34571.32871.67671.13671.159
72.01371.13771.23771.32371.3871.92971.45771.0771.72572.08771.52271.6271.10471.52571.37671.158
71.32571.38171.83371.08171.28171.12771.87271.46571.43471.90371.84471.6871.51971.49271.12471.684
71.12571.71271.90571.97871.80971.01872.05171.30671.6371.62471.60272.09971.42171.01971.95371.408
71.98871.47171.47271.41371.00471.62672.02471.20671.30371.08672.01371.95971.2971.62371.87272.075
71.95171.12272.01571.14871.79971.24271.85371.74371.14671.77471.96171.92471.28571.77171.26771.477一般来说，管子的直径可分为外径、内径、公称直径。管材为无缝钢管的管子的外径用字母Φ来表示，其后附加外圆直径的尺寸和壁厚，例如外径为68的无缝钢管，壁厚为18MM，用Φ68*18表示，无缝钢管，直缝钢管、镀锌钢管等采用DN表示，公称直径也叫公称通径，是管子(或者管件)的规格名称。管子的公称直径和其内径、外径都不相等，例如:公称直径为65MM的无缝钢管有76*10、73*12、70*14等等多种，其中76为管子的外径，10表示管子的壁厚，因此，该钢管的内径为(76-10-10)＝56MM，但是公称直径65不完全等于钢管外径减两倍壁厚之差(此处为56)，也就是说，公称直径是接近于内径，但是又不等于内径的一种管子直径的规格名称，在设计图纸中所以要用公称直径，目的是为了根据公称直径可以确定管子、管件、阀门、法兰、垫片等结构尺寸与连接尺寸，公称直径采用符号DN表示，如果在设计图纸中采用外径表示，也应该作出管道规格对照表，表明某种管道的公称直径，壁厚。
71.80671.99871.67771.84472.02671.49171.39371.44571.60972.01171.44471.07871.94571.32171.52371.844
71.77871.55571.16771.60271.88771.16471.80771.67971.32672.07271.63271.29871.92471.42671.85971.11
71.67471.30671.97171.74871.52471.33271.91371.23272.01772.03172.06172.0871.33871.65671.76571.238
71.99871.54571.21671.03771.76571.28571.34271.44571.46672.04671.42572.00371.40371.99971.83371.583
71.5771.73471.91171.62471.50871.15372.09371.0171.56971.98771.24871.06471.82371.93672.02171.349
71.32471.32771.79671.75671.87572.06971.05571.39971.32171.28471.30771.71371.70971.3871.00272.06
71.51871.55972.02571.94671.89771.53871.77771.9471.64271.19771.71471.95871.41471.65971.70771.616
71.16671.1671.50672.081