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Welding process of stainless welded steel pipe

Stainless welded steel pipe, referred to as welded pipe, is a steel pipe made of commonly used steel or steel strips after being crimped and formed by a unit and a mold. Welded steel pipes have simple production process, high production efficiency, many varieties and specifications, and less equipment investment, but the general strength is lower than that of seamless steel pipes. Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the varieties and specifications of welded steel pipes have been increasing. Heat exchange equipment has replaced seamless steel pipes with pipes, decorative pipes, medium and low pressure fluid pipes, etc.

The rust, oil, water, paint, etc. that are harmful to the welding should be thoroughly removed before the welding of the stainless welded steel pipe, and the electrode suitable for the steel type should be selected. The processing time interval of stainless welded steel pipe is shorter than that of carbon steel spot welding, and stainless welded steel pipe brush should be used to remove welding slag. After welding, in order to prevent local corrosion or strength reduction, the surface should be ground or cleaned.

At present, the stainless steel welding methods used in industry mainly include tungsten argon arc welding (TIG), high frequency welding, plasma welding and laser welding. Several welding methods have their own characteristics, but the most used are argon arc welding and high frequency welding. Tungsten inert gas shielded argon arc welding has high welding quality and good penetration performance. Its products have been widely used in chemical, nuclear and food industries, but its welding speed is not high. In order to improve the welding speed, some foreign companies have researched and developed a variety of methods. Among them, there is a welding method developed from a single electrode and a single torch to a multi-electrode multi-torch welding method, and the multi-torch argon arc welding is suitable for welding austenitic and ferritic stainless steel pipes. High-frequency welding is still a relatively new technology for welding stainless steel pipes. The welding speed is more than 10 times that of argon arc welding, but it is difficult to remove the burrs in the welded pipes. At present, high-frequency welded stainless steel pipes cannot be accepted by the chemical and nuclear industries. 

Laser welding technology is the latest welding technology. The welded steel pipe has very small weld seam, high welding quality and fast welding speed. It is suitable for welding high-quality stainless steel pipes. Germany, Japan and other countries have adopted this technology (some domestic enterprises). is also using this technique). Combined welding technology is to combine several welding methods to form a new welding process to meet people's requirements for the quality and production efficiency of stainless welded steel pipes. Japan, France and other countries have used certain combined welding technology for stainless welded steel pipe production.

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