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Case study on corrosion prevention for petrochemical spiral wet gas holders – Paint selection. The paint originally used has a molecular structure that provides good air and water permeability; it dries at room temperature during application, with the solvents evaporating slowly. At this time, impurities such as dust in the environment can easily mix in, causing numerous pinholes in the coating. In addition, conventional chlorosulfonated polyethylene coatings have poor adhesion, strength, and water resistance, and are prone to delamination, peeling, and severe discoloration. Therefore, increasing the service life of protective materials, preventing the deterioration of water quality in gas cylinders, and extending the usable period of that water are the main ways to improve the service life of gas cylinders. It is also the main basis for selecting materials and corrosion inhibitors. 1. Selection of corrosion-resistant materials (1) Selection of coating for the outer wall of the gas holder: The coating applied to the outer wall of the gas holder must not only have good water resistance and corrosion resistance, but also exhibit high adhesion, surface strength, and hardness of the paint film. In particular, the anti-aging properties of the protective material are essential. In terms of corrosion resistance, conventional oil-based materials have poor aging resistance and are not resistant to the erosion of acids, alkalis, and solvents. The use of chlorosulfonated polyethylene coatings can solve problems such as aging resistance, but the strength, adhesion, and decorative properties of these coatings remain unresolved. After evaluating the protective coatings available in our country, a resin-modified rubber high-weatherability composite coating (hereinafter referred to as high-weatherability composite coating) was selected; its gloss retention, aging resistance, and especially corrosion resistance are superior to those of conventional chlorosulfonated polyethylene coatings. The main components include silicone-modified epoxy resin, polyamide alkyd linoleic acid synthesis compound, chlorosulfonated polyethylene resin, and high-quality coating additives. Coatings that undergo addition reactions with epoxy resin, chlorosulfonated polyethylene resin, and other materials exhibit significant advantages over coatings using other crosslinking systems in terms of water resistance, heat resistance, chemical resistance, stability when stored as a single-component product, crosslinking speed, color stability, coloring ability, resistance to contamination, transparency of the clear coat film, and ease of dispersion during coating production. It is recognized abroad as the chlorosulfonated polyethylene coating type with the highest total score across these ten technical aspects. Its excellent performance has been demonstrated through actual production applications. (2) Selection of coating for the inner wall of the gas holder: Since the inner wall of the gas holder is not exposed to sunlight for long periods of time, the rate of aging of the coating is reduced accordingly; therefore, the coating only needs to be resistant to water and corrosion by various harmful substances. The inner wall of the original gas tank was coated with epoxy coal tar pitch as the topcoat. It can be seen that this coating meets the basic requirements, but there are still some issues regarding its impermeability; after some time of use, rust spots appeared on the surface, and cracking occurred in certain areas. To address the above issues, we modified the original coating by using an \"epoxy coal tar glass flake coating\"; this material is composed of modified epoxy resin, coal tar, glass flake fillers, thixotropic agents, and other components. Due to the presence of aliphatic short chains, ether groups, and highly reactive epoxy groups in its structure, epoxy resin possesses strong adhesion. Furthermore, epoxy resins contain a variety of polar groups as mentioned above; in particular, the epoxy group provides good wettability and adhesion to glass fibers. This is beyond what other commonly used thermosetting resins can achieve. In flake resins, the extremely thin glass flakes are arranged in a parallel and overlapping manner. When the thickness of the anti-corrosion layer is 1 mm, there are hundreds of layers of such parallel flakes, which create multiple barriers against the penetration of corrosive agents. The numerous intricate pathways effectively prevent the spread of these corrosive agents, thus granting the material a particularly strong resistance to their penetration. At the same time, since the glass flakes are present discontinuously within the resin, the shrinkage force is **reduced**, which also improves the crack resistance of the coating. Due to the excellent properties of corrosion-resistant materials possessed by this scale-resin coating, it is very suitable as a protective topcoat for the inner walls of gas tanks. 2. Selection of corrosion inhibitors: After analyzing the water quality in the gas holder and identifying the harmful impurities present in it, a formula for corrosion inhibitors was chosen based on domestic testing and screening; the main components of these inhibitors are triethanolamine acetate, quaternary ammonium salts, etc. The corrosion rate is approximately 0.000088 mm/a, and the protection level reaches 99.997%. The test results are shown in Table 1. As can be seen from the table, the use of the JF90-20 corrosion inhibitor yields an excellent protective effect, with a protection level of 99.997%.