The use of square pipes has penetrated into all areas of our society, but steel products have a shortcoming that is oxidized and rusted, and corrosion protection is imminent. There are many anti-corrosion processes such as oiling, galvanizing, and spraying, each with its advantages and disadvantages

Control from five aspects: human, material, machine, law and environment.① The human factor is the focus of welding control. Therefore, before welding, a skilled welder with a welder certificate should be selected, and necessary technical training and clarification should be conducted. It is not all