Dead characteristics: The maximum value of the wall thickness of the steel pipe on the same section, the minimum value exceeds the positive deviation and negative deviations, or the name of the nominal wall thickness is ± 8-10% (the upper limit of the thick wall tube is taken in the thin wall tube)
Reasons: The perforation is expected to meet the requirements. The tube end surface is incisive, the heating of the tube is unsatisfactory, the tube is heated unevenly, the perforated equipment is not adjusted properly, and the rolling machine is not adjusted properly.
