Use cellulose downward welding electrode welding of large diameter pipeline discussion
1 cellulose to theWelding Electrodecoating composition characteristics
1.1 cellulose electrode coating contains large amounts of cellulose (20% to 50%). J422 electrode covering almost free of cellulose ingredients.
1.2 cellulose electrode has a strong anti-rust and moisture resistance, good packaging, generally do not need to bake before welding.
2 cellulose performance characteristics to the process of welding electrodes
2.1 Arc force and sexual penetration. Produce large amounts of gas, so the arc has a strong blowing force and penetration resistance welding of cellulose electrodes.
2.2 arc moving direction from top to bottom, and simple to operate.
The 2.3 welding current. Same diameter welding wire, using the welding current to the welding electrodes over the previous 10% to 30%.
2.4 welding speed. Next is on the to weld root welding speed to weld breaking arc welding speed 3 to 5 times the the other weld bead is on the welding speed to the welding speed of 2 to 3 times.
2.5 weld layers. Downward welding speed welding, weld thickness compared to the previous welding thin same weldment welding on the number of layers is about 1.5 times the welding layers.
2.6 Electrode diameter. Electrode diameter is on the same wall thickness weldments used to weld to welding electrode diameter 1.2 to 1.3 times.
2.7 welding line energy. Although it is the same to the welding electrode diameter and welding current than the wall thickness of steel pipe welding increased significantly, but its increased welding speed more welding line energy.
3 cellulose to the quality characteristics of the Welding Rods
3.1 molding quality
(1) root pass and the back of the molding.
(2) the cap weld molding. Usually from 0.5 to 2 mm under the weld bead to the welding of each layer thickness is generally 2 ~ 3mm, weld reinforcement, molding appearance.
3.2 cellulose electrodes weld internal quality (NDT quality)
(1) drug skin contains a lot of cellulose to produce large amounts of gas welding, to prevent the intrusion of air, strong wind resistance.
(2) the process performance and operation due to fewer defects.
(3) weld layers, the thickness of each layer, the welding defects.
(4) The electrode has a strong anti-rust and moisture resistance.
Due to the above reasons, the cellulose to the weld having a good internal quality, easily through the non-destructive testing and inspection.
3.3 weld mechanical performance characteristics
Cellulose characteristics to the process of welding electrodes, weld small, together with welding speed, welding line energy weld heat affected zone is also small, so better welds and mechanical properties of welded joints. We have done a number of technology assessment, fully able to meet the requirements of the oil, gas and water supply and drainage pipe welding.