Three welding techniques for stainless steel welded pipes

At present, the welding methods of stainless steel welded pipes used in the industry mainly include argon arc welding, high-frequency welding, plasma welding, and laser welding. Several welding methods have their characteristics. At present, argon arc welding and high-frequency welding are the most used.

Stainless steel welded pipe technology - argon arc welding

Stainless steel welded pipe requires deep penetration, no oxide inclusions, and the heat-affected zone is as small as possible. Tungsten inert gas shielded argon arc welding has good adaptability, high welding quality, and good penetration performance. Its products are widely used in the chemical industry It is widely used in industries such as the nuclear industry and food. The low welding speed is the shortcoming of argon arc welding. To increase the welding speed, argon arc welding with a three-electrode welding torch is generally used. The wall thickness of the welded steel pipe is S≥2mm. The welding speed is 3-4 times higher than that of a single welding torch. Quality has also been improved. The combination of argon arc welding and plasma welding can weld steel pipes with larger wall thicknesses. In addition, 5-10% hydrogen in argon gas and a high-frequency pulse welding power supply can also increase the welding speed.

Stainless steel welded pipe technology - high-frequency welding

High-frequency welding has a higher power supply and can achieve higher welding speeds for steel pipes of different materials and outer diameters and wall thicknesses. Compared with argon arc welding, it is more than 10 times faster than its welding speed. Therefore, the production of stainless steel pipes for general purposes has high productivity. Because of the high speed of high-frequency welding, it is difficult to remove the burrs in the welded pipe. At present, high-frequency welded stainless steel pipes cannot be accepted by the chemical and nuclear industries, which is also the reason. From the perspective of welding materials, high-frequency welding can weld various types of austenitic stainless steel pipes. At the same time, the development of new steel types and the advancement of forming welding methods have also successfully welded ferritic stainless steel AISI409 and other steel types.

Stainless steel welded pipe technology - combined welding technology

Combined welding methods include argon arc welding plus plasma welding, high-frequency welding plus plasma welding, high-frequency preheating plus three-torch argon arc welding, and high-frequency preheating plus plasma plus argon arc welding. Combination welding increases the welding speed significantly. The weld seam quality of combined welded steel pipes with high-frequency preheating is equivalent to that of conventional argon arc welding and plasma welding. The welding operation is simple, and the entire welding system is easy to automate. This combination is easy to connect with existing high-frequency welding equipment. Investment Low cost and benefit. Various welding methods of stainless steel welded pipes have their advantages and disadvantages. How to maximize strengths and avoid weaknesses, and combine several welding methods to form a new welding process to meet people's requirements for quality and production efficiency of stainless steel welded pipes is a new trend in the development of stainless steel welded pipe technology.