Large -diameter spiral pipe joints not only affect the fineness of the pipe welding seams, constitute a pipe leakage, but also become the induction point of corrosion, which will severely reduce the strength and endurance of the weld. The elements of the large -diameter spiral tubes are: water, dirt, oxide and iron dumbs in welds, welding ingredients and coverage thickness, the surface quality of the steel plate, and the processing of steel plates, welding technology and steel pipe molding technology.
Then introduce relevant prevention and control measures
1. Reduce the secondary magnetic field. In order to reduce the effect of magnetic bias, the connection orientation of the welding cable on the workpiece may be only away from the welding terminal to prevent some welding cables from occurring the secondary magnetic field on the workpiece.
2. Technical aspects. The welding speed should be appropriately reduced or the current should be increased, and the crystallization speed of the metal of the welding seam melting tank should be delayed to facilitate the gas renewal. The bridge is maintained to form, forming a difficulty of gases.
3. Weld ingredients. When welding is rich in CAF2 and SIO2, it will re -absorb a large amount of H2, generate HF with high stability and insoluble in liquid metal, and then prevent the composition of hydrogen pores.
4. The stacking thickness of the weld is usually 25-45mm. The welded particles are large, the density is used to the maximum value, and the minimum value is taken; Or when the air humidity is large, the recycled solder should be dried before using it.
5. Square surface treatment. In order to prevent the open rolls from the falling of miscellaneous objects such as iron oxide leather to enter the molding process, the surface cleaning equipment should be set.
6. Steel board treatment. The steel plate should be provided with rust and burrs to eliminate the equipment to reduce the pores. After eliminating the orientation of the device, the best installation of the milling machine and the discs. The structure of the device is a active steel wire wheel that can adjust the gap on one side of the two orientation.
7. Welding seam description. The molding coefficient of the weld is too small, the shape of the weld is narrow and deep, and the gas and miscellaneous objects are not easy to emerge, and it is easy to form a pores and slag. Generally, the weld formation coefficient is controlled at 1.3-1.5, the thick wall welded pipe is maximum, and the thin wall is minimum.
