An introduction to the external anti-corrosion coating for pipelines: triple polyethylene (3PE)

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The production process for triple-layer polyethylene involves first spraying a layer of epoxy primer on the surface of the steel pipe. The pipe is then fed into the coating area at a certain rotational speed. The first extruder extrudes a film of adhesive in a specific thickness and density, which is wound around the surface of the steel pipe. While the adhesive is still in a molten state, the second extruder extrudes a polyethylene film that is wound around the adhesive to form the coating layer. The structure of the three-layer PE anti-corrosion coating is as follows: the bottom layer is FBE, with a thickness of approximately 50–127 mm; the middle layer is a copolymer adhesive, with a thickness of about 200 mm; and the outer layer is polyethylene, with a thickness of around 3 mm. This structure combines the high adhesion, oxidation resistance, chemical corrosion resistance, and cathodic disbondment resistance of FBE with the moisture resistance, electrical insulation, and mechanical damage resistance of high-density polyethylene, creating a perfect integrated system. It boasts outstanding advantages such as strong adhesion to pipe surfaces, excellent electrical insulation properties, impact resistance, and a long service life.