ASTM A554 welded stainless steel Mechanical Tubing

Stainless steel weld pipe heat treatment abroad widely used continuous heat treatment furnace with protective gas without oxidation, the intermediate heat treatment in the process of production and the final finished heat treatment, because of lack of oxidation of the surface of the light can get, and cancel the traditional pickling process.The adoption of this heat treatment process not only improves the quality of steel pipes, but also overcomes the environmental pollution caused by pickling.

Welding of stainless steel welded pipe

Argon arc welding

Penetration depth of molten stainless steel welded pipe requirements, do not contain oxide inclusions, heat affected zone as small as possible, argon arc welding of tungsten inert gas protection has good adaptability, high welding quality and good penetration performance, its products in the chemical industry, nuclear industry and food industry widely used.

Low welding speed is the deficiency of argon arc welding. In order to improve welding speed, many methods have been developed abroad.The welding method of multi - electrode multi - electrode multi - torch was developed from single electrode single torch.In the 1970s, Germany first used multiple welding torches arranged in a straight line along the weld direction to form a long heat flow distribution, which significantly improved the welding speed.Generally, three electrode welding torch is used for argon arc welding. The thickness S of steel tube wall is greater than 2mm, the welding speed is 3-4 times higher than that of single welding 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, 5-10% hydrogen in argon gas can be welded with high frequency pulse welding power, which can also improve the welding speed.
Multi - torch argon arc welding is suitable for austenitic and ferrite stainless steel pipe welding.

High frequency welding

High frequency welding has been used in the production of carbon steel welded pipe for more than 40 years, but it is a relatively new technology for welding stainless steel pipe.The economy of its production makes its products more widely used in the fields of architectural decoration, household appliances and mechanical structure.

High frequency welding has higher power power, and can reach higher welding speed for steel pipe with different material and wall thickness.Compared with argon arc welding, it is more than 10 times of its highest welding speed.Therefore, the production of general purpose stainless steel pipe has higher productivity.

Because of high frequency welding speed, it is difficult to remove the burr in the welded pipe.At present, high frequency welded stainless steel pipe is not acceptable for chemical and nuclear industries, which is one of the reasons.

From the perspective of welding materials, high frequency welding can weld various types of austenitic stainless steel tubes.At the same time, the development of new steel types and the progress of forming welding methods have also successfully welded steel types such as AISI409 of ferrite stainless steel.

Combination welding technology

Various welding methods of stainless steel welded pipe have their own advantages and disadvantages.How to foster strengths and circumvent weaknesses, several welding methods will be combined to form a new welding technology, meet the demand for stainless steel welded pipe quality and production efficiency, is the new trend of the current stainless steel welded pipe technology development.

Through the exploration and research in recent years, the combination welding technology has made progress, and the production of stainless steel welded pipe in Japan, France and other countries has mastered certain combination 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, high frequency preheating plus plasma plus argon arc welding.The combination welding increases the welding speed significantly.To adopt the combination of high frequency preheating welded steel pipe weld quality and conventional argon arc welding, plasma welding, the welding operation is simple, easy to implement the whole welding system automation, this combination is easy to interface with the existing high frequency welding equipment, low investment cost, the benefit is good.