PPH异径四通
  四通有等径和异径之分，等径四通的接管端部均为相同的尺寸；异径的四通的主管接管尺寸相同，而支管的接管尺寸小于主管的接管尺寸。四通是用于管道分支处的一种管件。对于采用无缝管制造四通来讲，目前通常所采用的工艺有液压胀形和热压成形两种。
   Four with equal diameter and different diameter of points, such as track four of the end part of the connecting pipe are the same size; reducing the four supervisor over the same size, and the branch pipe is smaller than the size of the pipe size over charge. Four is used for pipeline branch office of a pipe. The seamless pipe manufacturing, four, at present the technology with hydraulic bulging and hot forming two.