1. Environmental Conditions
Corrosive environments: Coastal environments, high salt spray, and chemical plant environments can accelerate zinc corrosion, shortening the lifespan to less than 15 years.
Humidity and Temperature: High humidity (>60%) or extreme temperature fluctuations can accelerate electrochemical reactions and reduce the corrosion protection effect.
2. Galvanizing Quality
Zinc Coating Thickness:
The standard thickness is ≥50μm (GB/T 5267.1), with a lifespan of up to 50 years indoors and approximately 20 years outdoors.
If the zinc coating is too thin (<40μm), the lifespan may be less than 5 years.
Workmanship Defects: Uneven coating, poor adhesion, or hydrogen embrittlement (for high-strength bolts) can significantly reduce durability.
3. Bolt Material and Construction
Base Material Strength: Bolts grade 8.8 and above must be protected against the risk of hydrogen embrittlement, and grade 10.9 bolts require special processing. Thread Design: Stress concentration areas (such as the thread root) are prone to premature failure due to fatigue cracking.
4. Installation and Maintenance
Installation Damage: Mechanical impact or excessive torque can damage the zinc coating; a torque wrench should be used to control this.
Insufficient Maintenance: Failure to regularly inspect the zinc coating for damage or reapply anti-rust paint can accelerate corrosion.
