30. What are the factors affecting the service life of hot-dip galvanized zinc coating? What is the general range?

(1) Thickness Considerations: The thickness of hot-dip galvanized coatings directly impacts their service life. Generally, maintaining a zinc layer thickness between 7-10 mm ensures optimal corrosion resistance and extended durability. Research indicates that coatings exceeding 3 mm can last 5-7 years, while those reaching 7-10 mm may last over 15 years.
Comparison: While hot-dip galvanizing may not outperform cold-dip galvanizing in thickness (with a range of 40-120 μm), it offers superior adhesion and corrosion resistance by forming an iron-zinc alloy layer.
(2) Environmental factors: The service life of hot-dip galvanizing varies depending on the environment. In industrial, urban, and coastal areas, where factors like air pollution, industrial emissions, and seawater corrosion are prevalent, the service life can last 15-20 years. In contrast, in rural or mountainous regions with fewer such factors, the service life may exceed 30 years.
Moisture and Corrosion: In humid, high-humidity or highly corrosive environments, the hot-dip galvanized zinc layer is prone to damage, leading to corrosion and deterioration, thereby shortening its service life.
(3) Material Quality and Manufacturing Process: High-grade hot-dip galvanized products are typically produced using premium steel through rigorous manufacturing processes and quality control. These products feature a uniform, dense zinc coating that provides superior resistance to corrosion and oxidation.
The process of hot-dip galvanizing includes degreasing, pickling, immersion in galvanizing solution, drying, heat treatment, hot-dip galvanizing, finishing and cooling.
(4) Regular Maintenance: Periodic maintenance is vital for extending the service life of hot-dip galvanized products. Regularly inspect and clean the zinc coating to remove dirt, water, and debris, and promptly address surface damage to prevent further corrosion and deterioration.