... the expanding pipe’s contraction problem (3% to 5%) of the original expanding machine and that saves copper, simplifies the process, this is the future directional pipe ... expanding machine. 1) It saves material, no material length contraction from the expanding part of workpiece ... ,Φ12.7,Φ16(Thickness),mm12.7,19.05,21.65,22,25.412.7,19.05,21.65,22,25.4 ...