Structure Description: Coating for the life of buried pipe is crucial The same material pipe buried in the ground for some decades without corrosion and leaks occurred a few years. It is because they use a different outer coating. Three-layer polyethylene protective layer, also known as three-tier PE is imported from abroad in recent years, advanced anti-corrosion technology. Its full name is Fusion Epoxy / Extruded Polyethylene Structure The protective layer structure consists of the following three layers: the bottom is fused epoxy (60-80μm); the middle layer is adhesive (170-250μm); the top layer is extruded Polyethylene (about 2mm). Protective layer total thickness greater than 22-29mm. Epoxy primer in the three-tier structure of the main role is: the formation of a continuous coating of steel pipe surface with direct bonding has good chemical resistance and resistance to cathodic disbonding performance; with the middle of the adhesive reactive groups react to form a chemical Bonding ensures that the overall coating has good adhesion at higher temperatures. The middle layer is usually a copolymer binder whose main component is polyolefins. Currently widely used vinyl copolymer adhesives. The polar part of the functional group of the copolymer adhesive can react with the epoxy group of the epoxy primer to form hydrogen bonds or chemical bonds to form a good adhesion between the middle layer and the bottom layer. The non-polar ethylene part and the surface polyethylene have the following advantages Good affinity so the middle layer and the surface layer also has good bonding properties. The main role of polyethylene surface layer is from the mechanical protection and corrosion with the traditional two-layer polyethylene coating has the same effect. Three-layer polyethylene coating combines the excellent properties of epoxy coating and extruded polyethylene two kinds of coating The epoxy coating interface properties and chemical resistance and extruded polyethylene coating mechanical protection features and other advantages Together they significantly improve their performance. Therefore, as a buried pipeline outer protective layer is very superior. According to the information on the three-tier PE can make buried pipe life of 50 years is currently considered in the international advanced pipeline anti-corrosion technology.