All metal surfaces in a cable tray system will be affected by corrosion over time. The type of corrosion, as well as its severity, depends on the physical properties of the metals used and the environment to which the cable tray is exposed.

Galvanic Corrosion

Galvanic corrosion occurs when two or more dissimilar metals are in contact while in the presence of an electrolyte (ie. moisture). An electrolytic cell is created, and the dissimilar metals form an anode or a cathode depending on their relative position on the Galvanic Series Table. The anodic material will be the one to corrode. Whether a material is anodic depends on its relative position to the other material on the galvanic series table.

For example: If zinc and steel are in contact, the zinc acts as the anode and will corrode over time; the steel acts as the cathode and will be protected. If steel and copper are in contact, the steel is now the anode and will corrode.

The rate at which galvanic corrosion occurs depends on several factors:

1. The amount and concentration of electrolyte present - An indoor, dry environment will have little or no galvanic corrosion compared to a consistently wet atmosphere.

2. The relative size of the materials - A small amount of anodic material in contact with a large amount of cathodic material will result in greater corrosion. Conversely, a large anode in contact with a small cathode will decrease the rate of attack.

3. The relative position of the two metals on the Galvanic Series Table – The further apart in the Galvanic Series Table, the greater the potential for corrosion of the anodic materia

To learn more, explore the Cable tray design considerations guide, cable tray web pages and brochure.

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