The purpose of the heating of the billet is to improve the plasticity of the steel, reduce the resistance to deformation, and provide a good metallographic structure of the steel for rolling the tube. 

There are four basic requirements for the heating of the billet or plate: 

① The temperature is accurate to ensure the best wearability Perforation within the temperature range;

② uniform heating, to ensure that the temperature difference between the horizontal and vertical of the billet is not more than 20 ℃; 

③ less burning loss, to ensure that the billet does not undergo oxidation during heating; 

④ no heating defects, to ensure that Heat cracking, adhesion, severe oxidation, overheating or overheating.