Standard for Galvanized Thickness of Cable Tray Cover Plates

The galvanized layer on a cable tray cover plate typically has a minimum local thickness of 45 µm for standard steel plates, with heavier components requiring ≥55 µm.

Typical Zinc Coating Thickness

For steel cable tray cover plates with a thickness of 1.5 mm to 3 mm, the local zinc coating thickness should be no less than 45 µm, which corresponds to a coating mass of at least 325 g/m². Heavier components, such as brackets or supports thicker than 3 mm, require a minimum zinc thickness of 55 µm to ensure adequate corrosion protection .

• Local thickness: Minimum value at any single test point, measured with a magnetic thickness gauge. All points must meet the requirement.
• Mean coating mass: Average zinc mass per unit area of the entire workpiece, determined gravimetrically, ensuring uniform protection across the surface .

Galvanization Methods

The thickness of the zinc layer depends on the galvanization process:

• Hot-dip galvanization: Steel is dipped in molten zinc, producing a thicker, more durable coating that covers all surfaces, including edges and joints. This method provides superior corrosion resistance, especially in outdoor or humid environments .
• Electro-galvanization: Produces a thinner, more uniform coating, typically used for indoor applications or where mechanical hardness is less critical .

Standards and Compliance

Standards such as GB/T 26941.1-2011 define the minimum zinc coating requirements for electro-galvanized trays, while international standards like IEC 61537 provide guidance on corrosion resistance and coating quality for cable tray systems . The galvanized coating should be continuous, uniform, and smooth, with minor imperfections like passivation films or water marks allowed, but defects that impair functionality (bare spots, blisters, rough nodules) are not permitted . In summary, for a typical cable tray cover plate, expect a zinc coating thickness of at least 45 µm, with thicker or structural components requiring 55 µm or more, depending on the galvanization method and environmental exposure.