Thickness Issues of Galvanized Layers: Hot-Dip Galvanized Cable Trays vs. Hot-Dip Galvanized Sheet Cable Trays

2025-11-24 00:55:36

Currently, test reports for hot-dip galvanized sheet cable trays issued by nationally recognized testing institutions are also based on JB/T 10216-2013. This standard specifies that the "surface protection layer thickness" shall be ≥ 65 μm. However, even if a thickness test is conducted (e.g., a result of 12 μm), no qualification judgment will be made for such cases.

The manufacturing of cable trays generally complies with JB/T 10216-2013. According to the standard, Galvanized cable trays are classified into hot-dip galvanized and electro-galvanized types, with galvanized layer thickness requirements of ≥ 65 μm and ≥ 12 μm respectively. In recent years, another type of cable tray—known as "hot-dip galvanized sheet cable tray"—has appeared on the market, which is directly made from factory-produced hot-dip galvanized sheets. This type of tray is not included in the JB/T 10216-2013 standard, so there are no specified requirements for its galvanized layer thickness.

According to research, the manufacturing standard for hot-dip galvanized sheets used in cable trays is GB/T 2518-2008 Continuously Hot-Dip Galvanized Steel Sheets and Strips, where coating requirements are specified in the form of weight per unit area.

Thickness Issues of Galvanized Layers: Hot-Dip Galvanized Cable Trays vs. Hot-Dip Galvanized Sheet Cable Trays

T/CECS 31-2017 specifies: The galvanized layer thickness (single side) of cable trays shall be ≥ 65 μm (equivalent to 460 g/m²). A thickness of 65 μm converts to a weight of approximately 460 g/m².

As shown in Table 3, only hot-dip galvanized sheets with a coating designation of Z600 can meet the thickness or weight requirements for hot-dip galvanized layers specified in JB/T 10216-2013 and T/CECS 31-2017, while those with a coating designation of Z450 are relatively close. Hot-dip galvanized sheets with other designations have significantly lower galvanized layer thicknesses. Undoubtedly, their corrosion resistance will also decrease accordingly compared to the standard requirement of ≥ 65 μm (460 g/m²).

From current test reports, the galvanized layer thickness of hot-dip galvanized sheet cable trays on the market ranges from just a few micrometers to over ten micrometers, indicating that most products use hot-dip galvanized sheets with smaller coating designations. This situation is expected to improve in the future, as Note 2 of Table 3.6.3 "Technical Indicators for Hot-Dip Galvanized Anti-Corrosion Layers" in T/CECS 31-2017 clearly states: "When factory-produced hot-dip galvanized sheets are used, the coating thickness shall comply with the requirements for Z600 specified in the current national standard GB/T 2518 Continuously Hot-Dip Galvanized Steel Sheets and Strips."