The reason why galvanized steel pipes do not rust easily is mainly due to the protective effect of the zinc layer, which blocks the contact between the steel matrix and the external environment.
Anti-Corrosion Principles
Physical barrier: the zinc layer covers the steel surface, blocking the erosion of the steel matrix by oxygen and water
Electrochemical protection: zinc is more active than iron. When the coating is damaged, zinc preferentially corrodes, protecting the steel matrix from rust
Dense corrosion products: the zinc layer forms a dense zinc oxide/zinc hydroxide film in the air, further slowing down corrosion
Usage Precautions
Avoid long-term exposure to strong acid/alkali environments to prevent the zinc layer from dissolving rapidly
When cutting and welding, the zinc layer at the cuts needs to be repaired to prevent local rust
Pay attention to the galvanized layer thickness and uniformity when purchasing, and inspect according to GB/T 13912