GB/T 30790.5-2014 "Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 5: Protective paint systems" specifies the types, system requirements, and selection guidelines for protective coatings used for corrosion protection of steel structures. It is adapted to different environmental classifications, surface preparation grades, and expected durability levels, covering various coating types such as water-based and high-solids coatings, and clarifies the applicability requirements for indoor, outdoor, and special scenarios. During testing, magnetic thickness gauges and eddy current thickness gauges are used to measure coating thickness, salt spray test chambers are employed to evaluate corrosion resistance, and cross-cut testers and pull-off adhesion testers are utilized to assess coating adhesion. This standard provides a basis for the selection and quality control of anti-corrosion coatings for steel structures.