1. Galvanized steel pipes are made by reacting molten metal with an iron matrix to produce an alloy layer, thereby combining the matrix and the coating. Hot-dip galvanizing is to pickle the steel pipe first. To remove the iron oxide on the surface of the steel pipe, after pickling, it is cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride and then sent to a hot-dip plating tank. The advantages of galvanized pipes are: uniform coating, strong adhesion, and long service life. Hot-dip galvanizing is because many companies now reduce the thickness of the galvanized layer to make profits. The original theoretical life is 7-8 years, and now the product quality can only be guaranteed for two or three years.

2. Fire-fighting plastic-coated steel pipe is a combination of steel pipe and plastic. It can be used for pipes of any caliber. The connection method is not limited to the threaded connection and groove connection of galvanized pipe but also includes welding connection, flange connection, bimetallic welding connection, etc. The emergence of plastic-coated steel pipes solves the above problems. It has the strength of steel pipe, and the inner and outer layers of steel pipe are anti-corrosive, making the inner and outer walls smooth, without reducing the flow diameter, and improving transportation efficiency. It is corrosion-resistant, has strong coating adhesion, good impact resistance, and can adapt to normal work in harsh natural environments. It has a long service life, which is more than five times that of galvanized pipe.