Precautions for seamless carbon steel pipe
Posted by zora li on October 21st, 2022
What should be paid attention to when welding seamless steel pipes? The following is the explanation of the staff of seamless steel pipe manufacturers, I hope to help you.
1. When docking and bottoming, in order to prevent the backside of the bottom bead from being oxidized, the backside also needs gas protection.
2. In order to prevent welding holes in special-shaped pipes, if there are rust or oil stains on the welding parts, they must be cleaned.
3. The dry elongation is generally about 5mm when the welding current is below 250A, and about 20-25mm when the welding current is above 250A.
4. The flat characteristic welding power source is adopted, and the DC welding adopts reverse polarity. Welding can be done with a normal CO2 welder, but the pressure on the wire feed rolls is slightly looser.
5. Arc length, MIG welding of stainless steel special-shaped pipe, generally under the condition of jet transition welding, the voltage should be adjusted to the arc length of 4-6mm.
6. MIG welding of special-shaped pipes is easily affected by wind, and sometimes the breeze will produce pores. Therefore, the wind speed should be taken where the wind speed is above 0.5m/sec.
7. The length of the tungsten electrode extending from the gas nozzle is preferably 4-5mm, the fillet welding and other places with poor shielding properties are 2-3mm, and the deep groove is 5-6mm. Generally no more than 5mm from the nozzle to the workpiece.
8. In order to make the argon gas well protect the molten pool and facilitate the welding operation, the angle between the tungsten center line and the welding workpiece should generally be kept at 80-85°, and the angle surface between the filler wire and the special-shaped tube should be as small as possible. Usually around 0°.
9. When using DC, the positive polarity is generally suitable for the welding of special-shaped pipes below 6mm. The welding is beautiful and the welding deformation is small. The protective gas is argon with a purity of 99.99%. When the welding current is 50-50A, the argon gas flow is 8-0L/min, and when the current is 50-250A, the argon gas flow is 2-5L/min.
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