The inner circle of thick plate is small, so the preheating flame is large when cutting thick plate, and the length of gas cutting flow exceeds 1/3 of the thickness of workpiece. The included angle between the cutting nozzle and the workpiece surface is about10 ~ 20, so that the edge of the part is heated evenly.

When cutting workpieces of different sizes on the steel plate, small pieces should be cut first, and then large pieces should be cut. When cutting narrow laths, leave 50mm at both ends of the length without cutting, cut the long side before cutting, or use the method of symmetrical cutting with multiple cutting torches. When cutting straight steel bars, it should be noted that the flame intensity of each cutting nozzle should be consistent, otherwise it is easy to produce lateral bending.