Resistance welding uses the resistance heat generated by the current flowing through the weldment and the contact point to heat the weldment locally and pressurize the weldment at the same time. For X52 steel pipes, no filler metal is required, the welding speed is fast, the deformation is small, and it is easy to automate. Its equipment, such as spot welding machines and seam welding machines, has outstanding advantages in the production of small-diameter or high-precision X52 resistance steel pipes, and can accurately control the heat input to ensure the size and appearance of the steel pipe. However, its joint strength is relatively limited and is not suitable for X52 steel pipes under high pressure.
Longitudinal submerged arc welding is arc welding under the flux layer. When welding X52 steel pipes, the arc between the welding wire and the steel pipe melts the three to form a metal molten pool to isolate the air. As the welder moves forward, the molten pool cools to form a weld, and the slag condenses into a shell. This process has stable weld quality, deep penetration, and high strength of the steel pipe after welding. The equipment includes submerged arc welding machines, flux conveying devices and wire reels, which can be flexibly adjusted according to the wall thickness of X52 LSAW steel pipes to ensure consistent quality. It is often used for large X52 steel pipe structures, but the equipment is complex and requires a large space for operation, which is inconvenient for welding small diameter and complex shape steel pipes.
Spiral submerged arc welding is also arc welding under the flux layer. For large diameter and thick wall X52 SSAW steel pipes, the welding path is spiral, the weld is distributed circumferentially, the pressure is evenly loaded, and the welding wire utilization rate is high. The equipment includes spiral submerged arc welding machines, etc., which perform excellently in the welding of oil and natural gas pipelines, with reliable weld quality and good corrosion resistance. However, after welding, the steel pipe has traces of spiral welds, and the appearance treatment requirements depend on the application, and the welding efficiency of small diameter steel pipes is poor.
API 5L Grade X52 ERW steel pipes
