Welding of stainless steel pipe

In recent years, as manufacturers have become increasingly concerned about environmental issues, car manufacturers are under increasing pressure to improve fuel efficiency. Stricter, more restrictive regulations bring technical challenges to industrial production and material processing. These trends include reducing emissions from emissions, lighter body, and extended service life.

Progress in the processing of materials has created a unique opportunity for the production of stainless steel pipe. Specifically, manufacturers are required to produce such parts, which must have lighter weight, but still have anti-corrosion characteristics and meet the strength requirements. In addition, the spatial limitations of the body more emphasis on the importance of formability. Typical applications include exhaust pipes, fuel pipes, fuel injectors and other components.

In the production of stainless steel pipe, the first forming a flat steel, and then make its shape into a round pipe. Once formed, the pipe joints must be welded together. This weld greatly affects the formability of the part. Therefore, it is extremely important to choose the right welding technology to obtain a welded profile that meets the rigorous testing requirements of the manufacturing industry. There is no doubt that tungsten gas arc welding (GTAW), high frequency (HF) welding, and laser welding have been used in the manufacture of stainless steel pipes.

High frequency induction welding In high frequency contact welding and high frequency induction welding, the equipment that provides current and the equipment that provides the squeezing force are independent of each other. In addition, both methods can use a magnet bar, which is a soft magnetic element, which is placed inside the pipe body, which helps to converge the weld flow at the edge of the strip. 

In both cases, the strip is cut and cleaned, rolled up, and then sent to the weld. In addition, the coolant is used to cool the induction coil used in the heating process. Finally, some coolant will be used for the extrusion process. Here, a great force is applied to the squeeze pulley to avoid perforation in the weld area; however, the use of a greater squeeze will result in an increase in burrs (or beads). Therefore, specially designed tools are used to remove the burrs inside and outside the pipe.

One of the main advantages of the high frequency welding process is that it can process high speed steel pipes. However, in most cases of solid forging, it is typical that high-frequency solder joints are not easily tested reliably using conventional non-destructive techniques (NDT). The weld cracks may occur in flat areas at low-strength connections, which can not be detected using conventional methods and may lack reliability in some demanding automotive applications.

Source: China Stainless Steel Pipe Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)