To ensure the tightness of the welded joint of stainless steel air duct, we can start from the following aspects.

Before welding, make preparations. First, cleaning, to thoroughly remove the oil, dust and other impurities in the welding parts and surrounding areas, because these may produce pores during welding, affecting the sealing performance, and can be cleaned with special stainless steel cleaner. The second is butt joint. It is necessary to ensure that the butt joint nozzle is flat and the butt joint clearance is even and appropriate, and the general clearance is about 0.5-2mm, so that the weld can be well formed.

The welding process is also critical. First, choose a suitable welding method, such as argon arc welding. Its shielding gas argon can effectively isolate the air and prevent the weld from oxidation, and the arc is stable and the heat is concentrated, which can make the weld high in quality and good in sealing. The second is to control welding parameters, such as welding current, voltage and welding speed. Excessive welding current is easy to cause defects such as undercut and burn-through; If the current is too small, there will be incomplete penetration, which will affect the sealing performance. Taking argon arc welding as an example, the welding current is usually around 80-120A, which should be adjusted according to the thickness of stainless steel duct.

After welding is completed, it should be inspected and treated. First, the appearance inspection, check whether there are obvious defects such as surface porosity and cracks in the weld, and repair them in time if there are defects. Second, nondestructive testing can be carried out, such as penetrant testing, to check whether there are tiny penetrating defects in the weld to ensure good sealing of the weld.