Points for Attention in Welding Seamless Steel Pipe

What should be paid attention to when welding seamless steel pipe? The following is the explanation of the staff of seamless steel pipe manufacturer, hoping to help you.


1. In order to prevent the back side of the bottom edge from being oxidized, the back side also needs gas protection when bottoming the butt.
2. In order to prevent the formation of welding holes of special-shaped pipes, if there is rust or oil stain, the welding parts must be cleaned.
3. Dry elongation, when the temperature is lower than 250A, the general welding current is about 5mm, and when it is higher than 250A, it is about 20-25mm.
4. Adopt flat characteristic welding power supply and reverse polarity for DC welding. Ordinary CO2 welding machine can be used for welding, but the pressure of wire feeder should be slightly relaxed.
5. Arc length, MIG welding on stainless steel special-shaped pipe, generally under the condition of spray transition welding, the voltage shall be adjusted to the arc length of 4-6mm.
6. The MIG welding of special-shaped pipe is easy to be affected by the wind, and sometimes there will be air holes in the breeze. Therefore, the wind speed should be used where the wind speed is higher than 0.5m/sec.
7. The length of the tungsten electrode protruding from the gas nozzle should be 4-5mm, 2-3mm in places with poor shielding performance such as fillet welding, and 5-6mm in deep groove. The distance from the nozzle to the work is generally no more than 5mm.
8. In order to protect the welding pool and facilitate the welding operation, the tungsten center line and the welding workpiece should generally maintain an angle of 80-85 °, and the angle surface between the filler wire and the special-shaped pipe should be as small as possible. Generally around 0 °.
9. When using direct current, it is usually suitable to use the positive pole for welding the special-shaped pipe below 6mm. The welding is beautiful and the welding deformation is small. The shielding gas is argon with purity of 99.99%. When the welding current is 50-50a, the argon flow is 8-0l / min, and when the welding current is 50-250a, the argon flow is 2-5l / min