Good pipeline weld experience!

Weld preparation Welding equipment: ZX7-400-3 welding machine is used for root welding; Bear Valley ZD-500 multi-function semi-automatic welding machine is used to fill and cover the surface. Welding materials: root welding using Bole Φ3.2E6010 cellulose electrode; Lincoln E81T8-Gφ2.0 flux core self-protective welding wire is used for filling and capping. Groove cleaning: before the group, the groove cleaning should be carried out first. Remove oil, rust, water and other dirt within 25mm of the groove and both sides of the groove with an Angle grinder or an electric wire brush until all the metallic luster is exposed. Nozzle alignment: Nozzle alignment directly affects root welding quality. It must be carried out in strict accordance with welding process parameters and the blunt edge of groove shall be controlled within the range of 0.5 ~ 2.0mm. The groove clearance is strictly controlled at 2.5 ~ 3.5mm, the top of the nozzle is 2.5mm, and the bottom of the nozzle is 3.5mm. Pipe orifice positioning welding: the orifice positioning is fixed with internal clips, 8 ~ 10 U-shaped clips can be used, evenly and symmetrically distributed in the orifice, and welded firmly. Then fix the weldment to the weldment frame at an Angle of 45°. welds 1. Select welding process parameters Welding process parameters are an important basis to guide welding operation. From root welding to filling and cover welding, welding process rules must be observed and welding process parameters must be strictly controlled. 2, root welding Preheating before welding: X70 steel has a high grade and a strong tendency to crack. It must be preheated before root welding by heating the groove and its surrounding area to 80 ~ 120℃ before root welding. Root welding: using E6010 cellulose down welding, double combination welding from pipe jacking. The welding joint starts from the point where the vertex exceeds the center line 5mm ~ 8mm. Arc is led from the surface of the groove, and then the arc is led to the root of the groove. After the blunt edge is fused, it is dragged straight down along the weld. The use of short arc operation, to prevent the generation of pores, conducive to groove root penetration, to prevent the generation of not weld penetration and fusion, at the same time to prevent the generation of concave and collapse, and do the replacement of welding rod at the full joint. After the root welding, the surface slag and splash should be completely removed, especially the junction between the weld and the groove surface should be cleaned up to avoid slag inclusion in the lower bead welding. 3. Filling welding The filling layer is E81T8-Gφ 2.0 flux core self-protective welding wire, and manual semi-automatic welding is adopted. X70 grade steel has a certain tendency to crack, in order to prevent cracking, it is necessary to ensure that the temperature between layers reaches more than 80℃, winter welding construction must take appropriate heating measures. After the root welding is completed, the welding layer should be cleaned immediately, followed by the welding of the hot welding layer and the filling layer; The welding defects of the filling layer are mainly porosity, slag inclusion and non-fusion. Keep short arc welding during filling welding; Adopt straight line or slightly swing; Continuously adjust the welding torch Angle from top to bottom to keep the welding wire Angle as shown in Figure 2; After each layer is welded, the slag must be cleaned up with a grinder or electric wire brush before the next layer is welded. When the filling layer is wide, row welding can be used. The lower pass should be arranged first and then the upper pass should be arranged successively, as shown in Figure 3. The weld pass should be uniform and full with good fusion on both sides. In particular, it should be noted that when filling the last layer, the groove edge should not be destroyed to ensure that the groove of the cover layer is clear, which provides a reference for the welding width control of the cover surface. 4, covering Cover welding should be qualified appearance size of the weld, no welding defects, beautiful shape, is the last procedure of the welding joint, is also the key procedure. There are prominent difficulties in the oblique 45℃ pipe cover welding. Defects such as underbite and ultra-high weld are easy to appear in the appearance, and grooves are easy to appear between the weld beads. Appropriate process methods must be adopted: Strictly according to the requirements of the process parameters, the straight line slightly swing bar, swing amplitude should be appropriate, melting on both sides of the groove edge 1.5mm ~ 2mm is appropriate, the swing bar, is conducive to gas precipitation and slag floating, can prevent the generation of pores and slag inclusion; When welding, it is necessary to first row the upper passage and then row the lower passage, which can not only appropriately reduce the number of row passes, but also easy to control the phenomenon of weld undercut, ultra-high weld pass and grooves between the weld passes. The transition between the weld passes is gentle, and the forming is beautiful, which is conducive to improving the quality and efficiency of the weld.铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods