Requirements for the thickness of galvanized layer in cable trays

The zinc coating thickness on cable trays typically ranges from 45µm for standard components to 65µm or more for hot-dip galvanized trays in highly corrosive environments.

Standard Thickness Requirements

• Electro-galvanized trays: For tray sheet metal with thickness between 1.5mm and 3mm, the local zinc thickness should be at least 45µm, corresponding to a coating mass of no less than 325 g/m². Heavier components like brackets and supports (>3mm) require ≥55µm to ensure adequate protection .
• Hot-dip galvanized trays: For outdoor or highly corrosive environments, the minimum zinc coating thickness is generally ≥65µm, providing strong adhesion, durability, and maintenance-free protection .

Measurement and Quality Considerations

• Local thickness: Measured at multiple points using a magnetic thickness gauge; all points must meet the minimum requirement .
• Mean coating mass: Represents the average zinc mass per unit area of the entire tray, often determined gravimetrically for arbitration purposes .
• Appearance: The coating should be continuous, uniform, and smooth. Minor dull areas or water marks are acceptable, but defects like bare spots, blisters, or excessive zinc dross are not permitted .

Corrosion Protection

The corrosion resistance of galvanized trays is directly proportional to the zinc layer thickness. Hot-dip galvanization provides a compact, durable layer that forms a protective patina over time, enhancing longevity in wet or industrial environments . Electro-galvanized trays offer thinner coatings suitable for indoor or less aggressive conditions .

Summary

• Indoor, standard trays: 45–55µm (electro-galvanized)
• Outdoor or harsh environments: ≥65µm (hot-dip galvanized)
• Thicker components: Require proportionally higher zinc thickness
• Measurement: Local and mean thickness must comply with standards to ensure corrosion protection and service life . Selecting the appropriate galvanized layer thickness depends on tray material, component size, environmental exposure, and applicable standards such as GB/T 26941.1-2011 or T/CECS 31-2017 .