What Is The Difference in Appearance between Pre Galvanized And Hot-dip Galvanized EMT Pipes

Pre galvanized and hot-dip galvanized EMT (electrical metal conduit) pipes have significant differences in appearance, mainly due to the differences in the two galvanizing processes. The following provides a detailed comparison of their appearance differences from multiple dimensions:

1. Thickness and texture of zinc layer

Pre galvanized EMT pipe:

Pre galvanizing (also known as electroplating) is the process of electroplating a thin layer of zinc (usually 3-5 μ m) onto the surface of a pipe after it has been formed.

Visually, the zinc layer is evenly distributed, with a delicate and smooth surface texture, and relatively weak reflectivity, presenting a soft silver white color.

Hot dip galvanized EMT tube:

Hot dip galvanizing is the process of immersing pipes in molten zinc solution, with a zinc layer thickness much greater than pre galvanizing (usually 40-50 μ m or more).

Visually, the surface of the zinc layer is relatively rough, and there may be subtle zinc nodules, zinc slag, or stripes (which are normal process phenomena). The texture is thicker, the silver white color is brighter, and the reflectivity is stronger.

2. Performance at the edges and interfaces

Pre galvanized EMT pipe:

Due to the thin and uniform zinc layer, the zinc layer covering the cut, edge or interface of the pipe is relatively neat, making it less likely to have obvious "exposed bottom" or zinc layer accumulation, and the overall appearance is more uniform.

Hot dip galvanized EMT tube:

The zinc layer is relatively thick, and there may be accumulation of zinc layer (such as rounded corners) or even slight burrs at the incision, edge or interface. This is because the molten zinc liquid is more likely to gather in these areas, which is a typical feature of hot-dip galvanizing process.

3. Appearance implications related to corrosion resistance

Although appearance cannot be directly equated with corrosion resistance, the thick zinc layer of hot-dip galvanizing will make the pipe look more "sturdy", while the thin zinc layer of pre galvanized will appear more "delicate". After long-term use, if the environment is humid, pre galvanized pipes may experience localized corrosion (such as spots) earlier, while hot-dip galvanized pipes may experience slower and more uniform corrosion.

Based on the above appearance features, the EMT tubes of the two processes can be visually distinguished, and the selection should be based on the actual usage environment (such as humid and corrosive scenarios, hot-dip galvanizing is preferred).