Before welding 3PE anti-corrosion steel pipes, it is necessary to first remove the external anti-corrosion layer of 50-100mm at the end of the pipe mouth, remove the oil, water, rust and other dirt within 20mm on both sides of the groove, so that it exposes the metallic luster, and then assemble, preheat, weld, insulate, and test according to the standard requirements; During the flange connection process of 3PE anti-corrosion steel pipe, an iron flange should be welded at one end of the 3PE anti-corrosion steel pipe