Environmental factors causing zinc layer detachment in pre galvanized EMT and IMC conduits

The zinc layer of pre galvanized EMT and IMC conduits is formed by electrolytic deposition, with limited adhesion and thickness, and is prone to detachment in the following environments:

1. Wet or high humidity environment

Long term exposure to rainy, dew forming, or high humidity (relative humidity>85%) environments can cause electrochemical corrosion of the zinc layer with water vapor, resulting in the formation of loose zinc oxide or zinc hydroxide (white rust) that gradually peels off the substrate. Outdoor exposure scenes such as underground garages, bathrooms, and rainy seasons.

2. Strong friction or mechanical impact environment

The pre galvanized zinc layer has low adhesion and is prone to detachment in frequent vibration, collision, or friction scenarios. For example, long-term friction between the inner wall of the conduit and the cable during cable threading; Temporary outdoor conduits are subject to wind shaking and impact; Collisions and scratches during the transportation and installation process.

3. Environment with high temperature or drastic temperature changes

The zinc layer is prone to thermal oxidation and discoloration above 100 ℃. Severe temperature fluctuations can cause an increase in the difference between the thermal expansion and contraction of the zinc layer and the substrate, leading to stress cracking and detachment. Such as electrical conduits near boilers, heating pipes, or outdoor exposed conduits exposed to sunlight in summer.

4. Corrosive medium environment

When exposed to media such as acid and alkali, salt spray, industrial waste gas (such as sulfur dioxide, hydrogen sulfide), etc., the zinc layer will be rapidly corroded and dissolved. Scenes such as chemical workshops, coastal high salt spray areas, sewage treatment plants, etc., even mild corrosion can accelerate the peeling of the zinc layer.

5. Scenarios of improper processing

If EMT and IMC conduits are galvanized and subjected to welding, cutting, or other processing, high temperatures will damage the surrounding zinc layer; Or if the coating is not protected during installation, contact with sharp objects can scratch the zinc layer, and the damaged area will become the starting point of corrosion, gradually expanding the range of detachment.