An introduction to the anti-corrosion coating of buried steel pipelines in the petrochemical industry

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The table lists the classifications and characteristics of anti-corrosion coatings for petrochemical pipelines. Type, Characteristics, Common Anticorrosive Coatings, External Anticorrosive Coating for Pipes, For Buried Pipes ； Resistant to corrosion by soil, salt, alkali, water, etc ； For above-ground pipelines ； Resistant to industrial atmospheric corrosion and weathering: epoxy coal tar coatings, epoxy powder coatings, polyester coatings, epoxy-polyester coatings, polyester-modified ethylene coatings, polyethylene coatings. Used for coating long-distance oil and gas pipelines (primarily for transporting crude oil, natural gas, and gas). Oil-resistant, does not contaminate the oil quality, has good impermeability (e.g., resistant to water and air penetration), and is corrosion-resistant. Epoxy coal tar coatings, epoxy powder coatings, epoxy-polyester coatings, epoxy-phenolic coatings, polyethylene coatings. Used for anti-corrosion coating of the inner walls of chemical pipelines (primarily for transporting liquid reactive materials such as acids, bases, ammonia, liquid chlorine, solvents, etc.). Resistant to chemical corrosion, acids and bases, temperature changes, water, and solvents. Epoxy coal tar coatings, epoxy-phenolic coatings, amide-modified ethylene coatings, polyepoxy powder coatings, polyethylene powder spraying (or using fiberglass pipes, enamel pipes, glass pipes, fiberglass-reinforced PVC pipes, fiberglass-reinforced polypropylene pipes). Used for coating water pipes and seawater pipes, as well as pipes in hydroelectric stations. Resistant to seawater, fresh water, impact, salt spray, and humid heat. Epoxy coal tar coatings, polyepoxy powder coatings (or using fiberglass pipes or rigid PVC pipes), polyethylene powder spraying. Used for coating slurry pipes and pipes used for transporting powders. Resistant to friction, with a low coefficient of friction, and corrosion-resistant. Epoxy-polyester coatings, polyester coatings. In China, for the external anti-corrosion protection of underground oil, gas, water, and heating pipelines, epoxy coal tar and asphalt coal tar paints are most commonly used as the anti-corrosion layer, polyurethane foam is used as the insulation layer, and polyethylene is used as the outer protective layer; this system is commonly referred to as the “double-layer protection” method. Large pipelines are provided with sacrificial anodes for combined protection.