Due to the use of square tube buried deep underground, in this environment it is easy to be corroded, so that the quality of the pipe does not allow much attention a little flawed, but because of a problem with the pipe, repair a lot of trouble, take it from underground dug trouble is dead, and I am in the quality strictly.
 Many of the shortcomings of the square tube is perforated so constituted square and rectangular tube in the mass production of reactive processes is vital program square tube. The primary high-alloy piercing tough piercing function is low, when necessary in order to ensure the quality of the rational selection of deformation parameters perforations. Squeeze a small amount would constitute a perforation process is unstable, so the amount of hours of critical crunch crunch former head probably amount is usually set at seven percent or so, otherwise it will not bite, perhaps even before the move to add the card. Increasing the amount of tightening the head in front of the bore and Chen Sheng will constitute a drawback inside so if you want to call in doubt the tube also centering, centering empty depth and contrast to be based on other kinds of steel. So the criteria is the future of the heating temperature and heating demand quality.
 The quality of the heating depends largely on the heating operation and heating guidelines. Small oval contrast coefficient values ​​generally conducive to enhancing the quality of the hair and to limit cross tube deformation. But nor too small oval coefficient, this will cause rolling rotation difficult, even resulting in the guides wear, easy on the surface constitute drawbacks. So the boat is probably the time when the bar across the square tube wear condition inspection guide, once discovered, immediately replaced, oval control of 1.07-1.08 degrees about the size inside. After the effects of normal as well as side-step process tube heating tube vital processes, which affect the quality of the finished product is also very large.