In recent years, domestic steel Structural engineering is developing from some traditional industries, such as bridges, power stations, water pipelines, oil pipelines, large petrochemical plants and storage tanks, offshore drilling platforms, to building steel structures. The production of building steel structures has the advantages of short cycles and intensive factory processing, and is gradually replacing traditional civil construction. However, steel structures have their own weaknesses and are prone to corrosion under exposed conditions, especially in humid areas, coastal areas, and industrial intensive areas. Due to the high levels of corrosive media such as SO2, CO2, and salt in the atmosphere, steel is severely corroded. For example, the corrosion rate of buried pipeline holes can reach up to 2.4mm/a, indicating how fast this corrosion rate is. So if effective anti-corrosion measures are not taken, steel components with huge investment will quickly be scrapped due to their own corrosion under exposed conditions, causing huge economic losses. From this, it can be seen that providing effective and long-term anti-corrosion protection has become a crucial link in the service life of steel structures.
Steel structures go through many processes from material surface treatment ->cutting ->welding processing ->anti-corrosion construction ->installation ->external surface anti-corrosion re treatment, among which the anti-corrosion coating process is an extremely important and easily overlooked key process. Corrosion prevention and rust prevention are actually a concept for steel structures. Metal corrosion can be divided into the following types: (1) Electrochemical corrosion, which is the main form of corrosion in steel structures (especially building steel structures) caused by the formation of batteries in the presence of water. The result is rust on the surface of steel. (2) Chemical corrosion occurs when steel undergoes high-temperature oxidation in the presence of oxygen at high temperatures. At this time, an anhydrous solution forms a micro battery, resulting in the formation of relatively dense oxide scales on the surface of the steel. (3) Biological corrosion, such as underground metal parts, greatly accelerates the rate of metal corrosion due to the involvement of microorganisms in the corrosion process in the underground soil. According to the types of corrosion products, metal corrosion can be further divided into film-forming corrosion (such as oxide skin formed by high-temperature oxidation) and non film-forming corrosion (such as rust generated by electrochemical corrosion). For steel components, electrochemical corrosion is often encountered and poses the greatest harm. Therefore, the anti-corrosion and rust prevention of building steel structures are mainly designed for electrochemical corrosion and biological corrosion. Steel structure anti-corrosion and rust prevention is a systematic engineering project, which mainly includes the following aspects of work to be done from a design perspective.
A. Design life of steel Structural engineering and durability expectation of coating system.
B. Assessment of the corrosion degree of the environment in which the steel Structural engineering is located.
C. In the budget of steel Structural engineering, the proportion of coating shall be taken, and the category of anti-corrosion coating shall be selected accordingly.
D. According to the type of coating, develop technical parameters such as steel surface pretreatment process, coating process, and coating thickness that meet the requirements.
E. Develop reasonable and operable quality testing methods for each process.
Source：http://www.cummins-jc.com/xueshulunwen/200810/09-28.html
