1. Double-sided argon arc welding process Summary Stainless steel storage tanks are generally atmospheric pressure containers with large volume and thin design wall plates. The commonly used welding process is manual electrode welding, which causes large spatter during welding, large welding internal stress, large deformation on one-sided welding, and difficult to control welding quality. Argon arc welding can overcome the above shortcomings, and there is no spatter and slag in the welding process. However, due to the strong oxygen affinity of stainless steel and its easy oxidation at high temperature, “slag-like welds” are prone to appear in the single-sided argon arc welding primer, resulting in “chromium depletion” in the weld joint area and premature failure in corrosive media. Moreover, single-sided welding is greatly affected by the groove group, and is prone to welding defects such as incomplete penetration and root fusion. In order to overcome the above defects of single-sided argon arc welding and the deformation caused by uneven internal stress of single-sided argon arc welding, and to improve the pass rate of non-destructive testing filming, it is now recommended to use two people to weld both sides of the weld at the same time, that is, double-sided argon arc welding process.
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3. Precautions for applying this process
1. Strictly control the quality of weld groove processing and weld assembly size (gap, misalignment, etc.). 2. The groove and heat-affected area must be cleaned and kept dry. 3. The welding process of the main welding side is exactly the same as the single-sided argon arc welding process. The auxiliary side welder must cooperate with the main welding side welder and keep the welding speed the same. The wire feeding speed is determined according to the shape of the molten pool and the welder’s experience to ensure that the inner wall weld is beautiful (auxiliary side). 4. The specifications of the argon arc welding gun magnetic nozzle are reasonably selected according to the thickness of the parent material and the size of the weld groove, and the argon gas flow rate is controlled to ensure that the weld pool and heat-affected zone are fully protected. 5. Two welders start and extinguish the arc at the same time. After the arc is extinguished, the argon gas continues to protect the arc pit for 1~2 minutes. 6. The wall plate positioning weld must be mechanically cleaned before formal welding.
4. Advantages of this process 1. Good welding quality, high pass rate of radiographic filming, and beautiful formation of the inner tank wall weld. 2. Small welding deformation and good formation of the outer tank wall weld. 3. Work efficiency is significantly improved (increased labor on the same working surface). 4. Reduce construction costs. No need for argon protection on the back of the weld, no need for root cleaning and grinding on the back of the weld, saving argon and labor.
5. Disadvantages of this process 1. Increased welding difficulty, requiring each group of welders to cooperate with each other and maintain the same welding speed. 2. High requirements for weld pairing, strict control of weld pairing gap.
Post time: Nov-18-2024
