The main advantages of submerged arc welding are: (1) Productivity The length of the submerged arc welding wire (the length of the wire from the end of the contact tip to the end of the arc) is much shorter than that of the manual arc welding, generally about 50mm, and It is an optical wire, which will not cause redness of the electrode coating due to the increase of current, and can use larger current (5-10 times larger than manual welding). Therefore, the penetration depth is large and the productivity is high. For butt welding below 20mm, it is not necessary to open the groove and leave no gap, which reduces the amount of filler metal. (2) The high weld quality has relatively perfect protection for the weld pool and less impurities in the weld metal. As long as the welding process is properly selected, stable and high quality welds are easily obtained. (3) Good labor conditions In addition to reducing the labor intensity of manual operations, arc arcs are buried under the flux layer, there is no arc radiation, and the working conditions are good.