GB/T 30790.2-2014 "Paints and varnishes – Corrosion protection of steel structures by protective paint systems – Part 2: Classification of environments" specifies the classification methods and basis for the corrosive environments in which steel structures are located. The standard categorizes corrosive environments into different classes by considering factors such as humidity, salt content, and pollutants, providing a fundamental basis for the design, selection, and performance testing of subsequent protective paint systems. By clearly defining environmental corrosion levels, it helps accurately match protective solutions and prevents corrosion protection failures due to improper environmental adaptation. It is applicable to the preliminary planning of corrosion protection for various steel structure projects.