Nowadays, the welding methods of stainless steel welded pipes used in industry mainly include argon arc welding, high frequency welding, Combined welding.

These three welding methods have their own characteristics. Currently, the most commonly used are argon arc welding and high frequency welding. In the following, we will introduce the three types of welding process technologies in detail.

Argon arc welding

Stainless steel welded pipes require deep penetration, do not contain oxide inclusions, the heat affected zone is as small as possible, and Tungsten arc welding with tungsten inert gas has good adaptability, high welding quality and good penetration performance. It is widely used in chemical, nuclear and food industries.

Low welding speed is the disadvantage of argon arc welding. In order 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, and the welding quality is also improved. The combination of argon arc welding and plasma welding can weld larger thickness steel pipes. In addition, 5-10% hydrogen in argon, and then using high-frequency pulse welding power, can also improve the welding speed.

High frequency welding

Frequency welding has a higher power than the power supply, and can achieve higher welding speeds for steel pipes of different materials and outer wall thicknesses. Compared with argon arc welding, it is more than 10 times its maximum welding speed. Therefore, the production of stainless steel pipes for general use has higher productivity.

The high speed of high-frequency welding, that makes a difficulty for removing the burr in the stainless steel pipe. At present, high-frequency welding of stainless steel pipes is not yet accepted by the chemical and nuclear industries.

From the perspective of welding materials, high-frequency welding can weld various types of austenitic stainless steel pipes. The development of new steel grades and advances in forming and welding methods have also successfully welded steel grades such as ferritic stainless steel AISI 409.

Combined welding

The combined welding methods are: argon arc welding plus plasma welding, high frequency welding plus plasma welding, high frequency preheating plus three torch argon arc welding, high frequency preheating plus plasma plus argon arc welding.

The combination welding improves the welding speed very significantly. For high-frequency preheating combined welded steel pipes, the quality of welding seams is equivalent to that of conventional argon arc welding and plasma welding, and the welding operation is simple. The entire welding system is easy to automate. Low cost and good benefits.

All in all, every welding method has its own advantages and disadvantages.

To combining welding methods to form a new welding process that to meet people’s requirements is a new trend in the current development of stainless steel welded pipe technology.