National Standard Thickness Specifications for Galvanized Cable Trays

For galvanized cable trays, the standard zinc coating thickness ranges from 12µm for electro-galvanized trays to 65µm for hot-dip galvanized trays, with tray sheet metal thickness typically between 1. 5mm and 3mm.

Tray Sheet Metal Thickness

The side plates and base plates of cable trays generally have a thickness of 1. 5mm to 3mm, while heavier components such as brackets and supports may exceed 3mm and require higher coating standards to ensure durability and corrosion resistance. Zinc Coating Thickness StandardsElectro-galvanized trays: Minimum zinc coating thickness is 12µm, suitable primarily for dry indoor environments due to limited corrosion resistance.

Hot-dip galvanized (HDG) trays: Minimum zinc coating thickness is 65µm, suitable for outdoor or highly corrosive environments, including bridges and industrial installations. Local thickness vs. mean coating mass: Local thickness refers to the minimum zinc thickness at any single test point, measured with a magnetic thickness gauge, while mean coating mass is the average zinc mass per unit area, determined gravimetrically for quality verification.

Appearance and Quality Requirements

The galvanized coating should be continuous, uniform, and smooth. Minor imperfections such as dull areas, passivation films, or water marks are acceptable, but defects like bare spots, blisters, rough nodules, or excessive zinc dross are not permitted. Environmental ConsiderationsElectro-galvanized trays are not suitable for sea freight or humid, chloride-rich environments, as thin coatings can quickly develop white or red rust.

Hot-dip galvanized trays provide superior protection in such conditions.

Compliance and Standards

National standards for cable trays often reference GB/T 26941. 1-2011 for electro-galvanized trays and other local regulations for hot-dip galvanization. Compliance ensures that cable trays meet mechanical, electrical, and corrosion resistance requirements for their intended application.

In summary, when selecting galvanized cable trays, it is essential to match the metal thickness and zinc coating to the environmental conditions and load requirements, ensuring compliance with national standards for safety and longevity.