Corrosion prevention measures for steel structures - Active corrosion prevention

Active corrosion protection modifies the steel's material or surface composition to reduce its reactivity with corrosive media. It is suitable for harsh environments such as coastal areas with high salt fog and chemical acid-base environments, and is the foundation for long-term corrosion protection.
1. Using Weathering Steel/Corrosion-Resistant Steel
Principle: By adding alloying elements such as copper (Cu), chromium (Cr), and nickel (Ni) to ordinary carbon steel, a dense oxide film (primarily composed of Fe₂O₃ and Cr₂O₃) forms on the steel's surface. This oxide film prevents further penetration of water and oxygen, providing a "self-protective" effect.
Common types:
(1) Ordinary weathering steel (such as Q355NH, suitable for inland outdoor environments): Corrosion resistance is 2-3 times that of ordinary carbon steel, commonly used in bridges, factory exterior walls, etc.;
(3) High weathering steel (such as 09CuPCrNi-A, suitable for coastal areas): Adding more chromium and nickel elements, salt spray resistance is increased by more than 50%, and can be used for offshore platforms and coastal factories;
(3) Stainless steel (such as 304, 316L, suitable for acidic and alkaline environments): Contains more than 18% chromium + more than 8% nickel, completely isolates corrosive media, and is commonly used in steel structure components of chemical workshops and food processing plants.
Advantages: No frequent maintenance is required, and the service life can reach 50-100 years. 2. Hot-Dip Galvanizing (HDG): The Core Anti-Corrosion Process During the Factory Prefabrication Stage
Principle: Derusted steel components are immersed in molten zinc at 440-460°C. A zinc-iron alloy layer (50-100μm thick) forms on the steel surface. This zinc layer not only isolates the corrosive media but also provides "sacrificial anode" protection (zinc corrodes preferentially, protecting the steel). It is currently one of the most commonly used corrosion protection methods for industrial components.
Applicable Components: Small, factory-fabricated components (such as purlins, bolts, and supports), and components exposed to frequent rainwater (such as roof gutters and downspouts).
Advantages: Long corrosion life (up to 15-20 years outdoors, over 30 years indoors), uniform coating, and strong adhesion.