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The internal coating of pipelines is a very effective measure to address the problem of internal corrosion in pipelines within gathering and transportation systems and water injection systems. After applying a coating inside the pipeline, it is possible to reduce the surface roughness, which in turn lowers the hydraulic friction coefficient when transporting gases. This allows for a smaller pipe diameter, thereby reducing the material and construction costs associated with the pipeline. Common technical methods include epoxy powder coating technology, liquid epoxy coating technology, and other coating application techniques. 1. Epoxy powder coating technology: Epoxy powder coatings feature low viscosity, good film leveling, a smooth and even appearance, strong adhesion, high film hardness, excellent corrosion and chemical resistance, no by-products during curing, good applicability, and high utilization efficiency. There are many methods for applying epoxy powder, such as electrostatic spraying, thermal spraying, vacuum suction coating, and fluidized bed method. For coating large-diameter pipes inside pipelines, electrostatic spraying is generally used; for small-diameter pipes, the fluidized bed hollow cone atomization spraying method or vacuum suction coating is typically employed; while for irregularly shaped parts, the fluidized bed method is usually used. 2. Liquid coating technology: Liquid epoxy coatings use epoxy resin as the main component for forming the film, with amine-based curing agents being commonly used. Liquid epoxy coatings possess extremely strong adhesion, excellent corrosion and wear resistance, as well as good physical properties; however, their applicable thickness is limited, preventing them from achieving the desired levels. Liquid epoxy coatings for the inner surface of pipes can be applied using methods such as air spraying, cup electrostatic spraying, and high-pressure airless spraying. 3. Other coating technologies: Chlorinated rubber coatings possess excellent adhesion, resistance to chemicals, and weather resistance; they are easy to apply, and as primary coating materials they are widely used in the petrochemical industry. Oilfields such as Daqing, Shengli, Jianghan, and Zhongyuan have all adopted Ni-P alloy electroless-plated tubing, which not only reduces costs but also achieves certain effects in corrosion prevention.