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This post was last edited by Wang Wei2 on 2024-2-27 08:10. Several mistakes to avoid in the anti-corrosion management of equipment, steel structures, etc. Paints are widely used in the industrial sector, but there are several misconceptions in practical applications such as anti-corrosion design, material selection, bidding processes, and application of anti-corrosive coatings: 1. Focusing too much on anti-corrosion materials while neglecting surface treatment. ① Before applying anti-corrosive coatings to metal or non-metallic materials, it is necessary to pre-treat the surface of the substrate; this is a very important step in anti-corrosive coating applications. If the surface treatment is not done properly, it will directly affect the adhesion of the coating to the substrate, the quality of the coating, its protective capabilities, its service life, and its appearance. It has been found that the quality of surface treatment is the main factor affecting the quality of the coating. ②Surveys of several major petrochemical companies have shown that the main factor preventing anti-corrosion coatings from lasting as long as designed is inadequate surface treatment, which accounts for over 50% of the problems related to material selection, compatibility, and environmental conditions. This is especially true for steel structures, as well as for uninsulated storage tanks, reaction vessels, and the outer walls of pipes in plant areas. In some cases, pitting occurs on the steel structures of pipe racks and the outer walls of storage tanks within just six months, while extensive rusting starts within less than a year, resulting in the discharge of yellowish liquid. ③The relevant parties are only concerned with the quality of anti-corrosion coatings, their performance in industry applications, and their economic benefits; they ignore the requirements related to surface treatment. In fact, they attribute the basic surface treatment requirements we propose to the harsh conditions under which anti-corrosion coatings are applied. As a result, they are reluctant to invest money or effort in surface treatment, which inevitably leads to a **shorter lifespan of the anti-corrosion protection. 2. Emphasis on material selection, neglect of anti-corrosion components ① Since anti-corrosion coatings have varying properties, different choices should be made depending on the environmental conditions, the characteristics of the surface to be coated, the construction conditions, and the intended lifespan of the anti-corrosion protection. Therefore, it is not sufficient to simply judge anti-corrosion coatings as “good” or “bad”; rather, they should be selected as part of a whole, considering their compatibility with other components. ②Supporting considerations include factors related to external conditions as well as those related to the coating itself, such as the properties of the substrate to be coated, the reapplication suitability of the base, intermediate, and top coats, corrosion conditions, the film-forming/curing conditions of the coating, surface treatment requirements, the coating thickness, the painting method, the design lifespan for corrosion protection, and technical and economic indicators. ③In actual business practices, it is common to see a lack of attention to the compatibility of anti-corrosion systems. In some projects, high-quality anti-corrosion coatings are used, designed for long-term protection – consisting of an epoxy zinc-rich primer, an epoxy intermediate coat, and a polyurethane top coat – yet the surface treatment relies only on power grinding to achieve ST2/ST3 standards, or even just the use of electric steel/copper brushes for surface cleaning; such methods are far from sufficient to meet the requirements for long-term corrosion protection over 8 years or more ； Some surface treatments use sandblasting to achieve a Sa2.5 standard, yet red lead is used as the primer – \"wearing a dress while putting on straw sandals\"” ； Especially in maintenance work, when repainting over existing coatings without considering the compatibility between the new coating and the old one, problems such as delamination and bubbling occur, leading to failure of the painting process. 3. Focus on the unit price of materials while neglecting the overall cost. ① Compared to other options, anti-corrosion coatings with better performance are produced by large manufacturers; due to constraints in the selection of raw materials and the technical complexity of their products, their production costs are higher, resulting in a higher price per liter (kilogram). However, since many of these products have a high solid content, they allow for a larger coating area at a given thickness, so under the same designed thickness, the overall cost of such anti-corrosion coatings is not high, while their quality improves significantly. Therefore, in the technical and economic comparison of anti-corrosion coatings, attention should also be paid to the coating area and coating lifespan. ②There are many factors that influence the cost of anti-corrosion coatings in anti-corrosion construction; these can be summarized as: designed film thickness, performance parameters of the coating (such as solid content), coating loss, and application methods. ③Some users often pay attention only to the unit price of the materials and do not calculate the total cost; as a result, they choose low-cost anti-corrosion coatings produced by small factories. Such coatings have poor quality, a low solid content, and a limited coating area, which means that the overall cost ends up being high. This phenomenon is extremely common. 4. Emphasis on short-term investments, neglect of long-term costs. ① “Anti-corrosion maintenance is needed every year, just in varying degrees,” is a humorous way of describing the issue of corrosion control in the petrochemical industry. Surveys of several large petrochemical companies show that more than 70% of the steel structures in these facilities begin to rust after three years; after five years, they are completely ruined. The steel structures in pipeline corridors also become heavily corroded after five years, and the same situation applies to pipelines without insulation. ②When selecting a corrosion protection coating system, a technical and economic comparison should be conducted. Different corrosion resistance lifespans should be assigned to various projects, in order to avoid choosing systems with overly short lifespans. Although such systems may seem to have low initial costs, they incur high maintenance expenses later on; due to the complexity of maintenance, the costs associated with subsequent maintenance for many projects can even exceed the initial investment. ③The corrosion resistance lifespan after maintenance is usually not as good as that achieved by using a coating system with a longer service life at the time of construction. In the total investment of petrochemical projects, corrosion protection accounts for only a small proportion; therefore, to ensure the long-term operation of the facilities, it is entirely feasible to choose a coating system with a longer lifespan, thereby reducing the need for subsequent repairs. This approach helps avoid disruptions in normal production due to inadequate corrosion protection, as well as increased maintenance costs.