Stainless steel welded pipe requires deep penetration, no oxide inclusion, and the heat affected zone is as small as possible. Argon arc welding with tungsten inert gas protection has good adaptability, high welding quality and good penetration performance. Its products are widely used in chemical industry, nuclear industry and food industry.

　　Low welding speed is the disadvantage of argon arc welding. In order to improve the welding speed, three electrode torch is generally used for argon arc welding. The wall thickness of welded steel pipe is s ≥ 2mm, the welding speed is 3-4 times higher than that of single torch, and the welding quality is also improved. The combination of argon arc welding and plasma welding can weld steel pipes with larger wall thickness. In addition, the welding speed can be improved by using high frequency pulse welding power supply with 5-10% hydrogen in argon.

　　Technology of stainless steel welded pipe high frequency welding

　　Frequency welding has higher power, and can achieve higher welding speed for different materials, outer diameter and wall thickness of steel pipe. Compared with argon arc welding, its welding speed is more than 10 times. Therefore, the production of general-purpose stainless steel pipe has high productivity.

　　Because of the high speed of high frequency welding, it is difficult to remove the burr in welded pipe. At present, high frequency welded stainless steel pipe is not accepted by chemical industry and nuclear industry, which is one of the reasons. From the welding material, high frequency welding can weld all kinds of austenitic stainless steel pipe. At the same time, with the development of new steel grades and the progress of forming welding methods, ferritic stainless steel aisi409 and other steel grades have been successfully welded.