What are the requirements for welding technology of stainless steel pipe fittings?

Due to the different sizes of stainless steel pipe fittings, according to the unique welding of stainless steel pipe fittings, the heat input should be reduced as much as possible, so two methods of manual arc welding and argon arc welding are used. Arc welding cover. d≦Φ159 mm all use argon arc welding. The welding technology of stainless steel pipe fittings needs to meet the following conditions.
①The welding machine adopts DC reverse connection during manual arc welding, and DC forward connection during argon arc welding;
②Before welding, the oxide skin on the surface of the welding wire should be brushed off with a stainless steel wire brush, and washed with acetone;
③ Before welding, clean up the oil stains within 25 mm on both sides of the workpiece groove, and wash the 25 mm range on both sides of the groove with acetone;
④ During argon arc welding, the diameter of the nozzle is Φ2 mm, the tungsten electrode is a pot tungsten electrode, and the specification is Φ2.5 mm;
⑤ When welding stainless steel by argon arc welding, the back side must be protected by argon gas to ensure the back side is formed. The method of filling argon locally in the pipeline is adopted, the flow rate is 5-14L/min, and the front argon flow rate is 12-13L/min.
When bottom welding, the thickness of the weld should be as thin as possible, and the fusion with the root should be good. When the arc is closed, it should be in a gentle slope shape. The arc must be ignited and extinguished in the groove, and the crater should be filled when the arc is extinguished to prevent crater cracks.
Since the stainless steel pipe fittings are austenitic stainless steel pipes, in order to prevent carbide precipitation sensitization and intergranular corrosion, the interlayer temperature and post-weld cooling rate should be strictly controlled. Immediately water cooling, while using segmented welding. This symmetrically dispersed welding sequence can increase the cooling rate of the joint and reduce the welding stress.

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