the anti-corrosion of plastic-coated steel pipes has developed from the earliest inner and outer polyethylene, due to adhesion problems, to inner and outer epoxy, but the outer epoxy layer is not resistant to bumps, and later developed to the third generation of inner epoxy outer polyethylene, but single-layer polyethylene directly combined with steel pipes still has adhesion problems, and finally upgraded to the fourth generation of anti-corrosion-3pe external anti-corrosion fusion-bonded epoxy powder internal anti-corrosion pipe. the outer 3pe inner fusion-bonded epoxy composite steel pipe is widely used in the water conservancy industry, municipal industry, and long-distance water pipelines, such as: supporting projects for south-to-north water diversion.