Spiral welded steel pipe defect prone areas have porosity, thermal cracking, and undercut. Spiral steel pipe seam weld porosity affects not only dense, causing pipeline leak, and will become a point of corrosion-induced, severely reducing weld strength and toughness.
To avoid uncoiling leveling off of iron oxide and other debris into the molding process, the board should be set up cleaning device. In submerged arc welding, the inner weld hot cracking, and particularly in the arc of the arc crater cracks occur easily. To eliminate this crack, usually in the extinction of the arc and plate fitted and welded at the ends of the coil can be reversed and the spiral welded steel pipe welded into the stack. Heat stress is a big crack in the weld when the weld metal is high or when the most prone. Steel plate edge should be set rust and burrs removal device to reduce the possible porosity. Clear device installed in the best location and disc cutting edge milling machines, structure of the device is the active wire wheel while two position adjustable gap down, up and down the compression plate edges. Involved in the welding slag. Is involved in the remaining part of the slag welding slag in the weld metal. Weld's form factor is too small, narrow and deep weld shape, gas and inclusion is not easy to leak out, easy to form pores and slag. General weld factor control in 1.3-1.5, take the maximum thick-walled spiral pipe, thin-walled take minimum. Penetration of the poor. Inside and outside the weld metal overlap is not enough, and sometimes lack of penetration. This situation is called a lack of penetration degrees.
To reduce the effects of magnetic blow, so that the connector position on the workpiece away from the welding cable welding may only terminal part of the welding cable to avoid the secondary magnetic field generated in the workpiece. Undercut is a V-shaped groove along the edge of the seam weld centerline. Undercut under welding speed, current, voltage, and other conditions resulting in inappropriate. Which is too high welding speed than the current does not fit easily cause undercut defects. In the process should be appropriately reduced welding speed or increase the current, thereby delaying the crystallization rate of the weld metal bath, in order to escape the gas, while the delivery position is unstable if the strip should be timely adjusted by trimming the front to prevent the frequent After the bridge or bridge to maintain shape, causing gas to escape difficult.
