Black erw steel pipe is hot-rolled coil through the molding machine, the use of high-frequency current skin effect and proximity effects, so that the edge of the tube heating and melting, in the role of squeeze roller pressure welding to achieve production.
Black erw steel pipe, compared with ordinary welding technology is not the same, the weld is made of the base material of the steel body melting, mechanical strength better than the general pipe. Smooth appearance, high precision, low cost welding seam height, favorable 3PE anti-corrosion coating. High-frequency welded steel pipe and submerged arc welded pipe welding methods are significantly different. As the welding is completed at high speed instantly, to ensure the quality of welding is much more difficult than submerged arc welding.