There are some detailed matters need attention when welding stainless steel pipes.
1. Applied the vertical generator characteristic power, when using the direct current, apply the positive polarity (welding wire connect to negative polarity). Generally is suitable for welding thin plate about 6mm. When using this method, the pipe will have better appearance and small welding deformation.
2. The protective gas is argon with a purity of 99.99%. When the welding current is 50 to 50A, the flow rate of argon gas is 8 to 10L/min; when the welding current is 50 to 250A, the flow rate of argon gas is 2 to 5L/min.
3. The best length of tungsten electrode is 4 to 5mm, in position with poor fillet welding, it is 2 to 3mm, in deep slot is 2 to 3mm, the distance between nozzle and body part should no more than 5mm.
4. Clean the rust and greasy dirt on welded parts, in order to prevent welding porosity.
5. In terms of the length of welding arc, when welding ordinary steel, 2 to 4mm is appropriate, when it comes to stainless steel pipes, the length should more than 3mm, otherwise will reduce its protective effect.
6. When backing welding, the back side of pipes also needs protective gas so as to avoid the oxidized back.
7. The angle between tungsten electrode centerline and welding workpiece should be maintained 80 to 85 °, the angle between the surface of workpiece and welding wire should be as narrow as possible, generally about 0 °. The purpose of keeping proper angle is to give better protection to welding pool and convenient for operation.
8. Windproof and ventilation. When welding in windy place, please take block network or other measures, while in the indoors, it’s better to take appropriate measures for ventilating.