Centralized repair welding method for arc welding with oil, water and pressure electrode
01 Selection of power supply, welding materials and power supply Dc welder is used for manual arc welding power supply.Materials are selected according to the different materials of the base material.In general, alkaline low hydrogen electrode is selected, because the viscosity of the electrode is larger, the molten metal in the molten pool is not easy to be blown away, and the welding current is 35% ~ 60% higher than the current in each position under normal conditions, as shown in the attached table, to enhance the arc blowing force, improve the fusion, improve the temperature of the molten pool and base metal.In the flat welding position, the larger current is selected, and the first molten pool is formed by arc-shaped track at the upper end of the groove downward. Then the arc is gradually pulled forward from back to quickly arc. After the molten pool is solidified, the previous step is repeated.Stay in the leak point groove as short as possible to prevent liquid metal from being blown away.When welding in climbing position, welding from top to bottom, while increasing current, low arc, using arc blowing force and droplet weight, will fill the leak point.In the inverted welding position, a section of casing with a diameter slightly larger than that of the leakage pipe can be used to cover the leakage point, and the part without pressure can be welded completely. Finally, the leakage point can be completely blocked in the flat welding position.03 common leakage methods and treatment methods (1) in the leakage is not serious, can be directly blocked by electric arc welding.First determine the location and size of the leakage point, with a small hammer on the leak, as much as possible to minimize the leakage point, and then start welding.When welding, the arc can not be directly blown to the leakage point, so as not to burn through and cause larger leakage point.Cylindrical shape should be welded around the leakage point first, and then gradually filled in the cylinder to make the leakage point smaller.The final sealing, with a small hammer can be sealed.If there is leakage, use spot welding method for treatment.(2) In the leakage pressure is large but the area is small, you can use the method of mounted saddle leak plugging.The specific method is to use the knot wire with the same diameter or slightly smaller diameter of the leakage steel pipe to plug, first repair the knot wire with the inner wire buckle into the saddle mouth, then ride the saddle mouth at the leak point, and then weld the saddle mouth well, after welding, plug the wire to stop the leakage, as shown in Figure 1.Figure 1 Knot wire plugging (3) In the case of large pressure and area of leakage, it is advisable to plug the leakage by welding casing.Specific methods:Is with a diameter slightly larger than steel pipe section of casing leak, to repair make both ends with the leaking pipe diameter consistent nozzle, and then along the casing axial cut in half, open a hole in the top half of the pipe, weld a small valve in the hole, then the two half casing buckle in leaks, alignment positioning, the longitudinal seam after welding the small valve open to the lower casing,Start welding base and girth welds at both ends, close valve after welding, as shown in Figure 2.(4) Sealing is the last procedure and the most important step of manual arc welding, and it is also difficult. Because fluid leaks from this point, molten droplets are easy to be blown away, and it is difficult to fuse with the base metal.Therefore, it is advisable to use the following method for processing: first, when the leakage point is a small round hole, a section of asbestos rope can be used to press into the hole, and then hit with a small hammer, and then gradually welded from the outside, welding arc can not be directly blown to the leakage point.Second, when the pressure is relatively large, the pointed steel bar can be inserted, and then hit flat with a hammer, and finally hit flat steel bar welding.If it cannot be completely sealed, it can be smashed flat after spot welding on one side, and this method can be used repeatedly until it is completely sealed.Third, when there is pressure, but not too much and the area of the leak point is large, it is advisable to use the method of casing welding to plug the leak, when the pressure is large and the area is small, the method of saddle plugging can be used to plug the leak.Fourth, in order to ensure the strength of the weld, the butt weld can be added to the back plate first, so as to reduce the impact of fluid on the weld and ensure the strength of the weld.(1) This method is not suitable for the leakage of inflammable and explosive fluids.(2) For the pressure trap, fluid is corrosive leakage point, before starting to fill the leak, the thickness of the welding part should be measured, if the thickness is too small, it should not be carried out to prevent danger.(3) In the process of filling the leak, the construction personnel must carry out systemic safety protection.(4) The force at the hammer should not be too large to prevent further cracking at the leakage place due to vibration.