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.

Answers

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