Pre-galvanized pipes are manufactured by coating a layer of zinc onto the surface of cold-rolled or hot-rolled steel sheets, forming galvanized sheets, and then processing and welding them into pipes. The iron material is manufactured first, and then galvanized. Hot-dip galvanized pipes, on the other hand, are manufactured by immersing the iron pipe in molten zinc after it has been cooled to a certain temperature, allowing the iron and zinc to react and form a zinc layer. In other words, the galvanizing process for hot-dip galvanized pipes is performed after the pipe is manufactured.

In terms of appearance, pre-galvanized pipes have a silver-gray appearance, a smooth surface, and good corrosion resistance. However, their corrosion resistance is relatively limited, making them suitable for applications requiring a smooth surface. They are corrosion-resistant, wear-resistant, and have high strength, but if used in a humid environment for extended periods, the zinc layer can easily corrode and peel off, significantly reducing their corrosion resistance.

Hot-dip galvanized pipes have a silver-white appearance, a rough surface, and even better corrosion resistance. They have good corrosion resistance, a long service life, and can adapt to various harsh environments, thus having a wider range of applications. However, its drawback is that the surface is relatively rough, making it unsuitable for applications requiring high surface finish.

Generally, the thickness of a single-layer FBE coating is 300–450 μm, but for some special applications, the thickness may reach 1000 μm.

The corrosion protection effect of double-layer FBE coatings can be divided into standard and reinforced grades depending on the coating thickness. The standard grade coating thickness is 600 micrometers, while the reinforced grade reaches 800 micrometers.