The reason why hot-dip galvanized pipes are mostly used in firefighting

Hot-dip galvanizing was invented in the mid-18th century. It was developed from the hot-dip tin plating process and has a history of more than 300 years. To this day, hot-dip galvanizing is still a widely used and effective processing method for steel corrosion resistance.

The principle of galvanizing to protect steel is as follows: in addition to forming an outer layer to prevent air and moisture from corroding the steel pipe, the iron used is more electronegative than zinc. By preferentially oxidizing the galvanized layer, A sacrificial layer of zinc protects the steel inside. Therefore, the corrosion resistance of ordinary welded pipes is unmatched. Even steel that has been treated with anti-corrosion methods such as oiling and painting has no corrosion resistance compared with hot-dip galvanized pipes.
The galvanized layer of hot-dip galvanized pipe is a shell covering the surface of the steel pipe after soaking, while the cold-dip galvanized pipe is a layer of plastic film formed through electrolysis, so the galvanized layer of hot-dip galvanized steel pipe is much thicker. Far away high supercooled galvanized pipe. From the basic principles of galvanizing to protect steel, we can understand that the thicker the galvanized layer and the larger the zinc, the better the protection effect on steel. Therefore, the thickness of the galvanized layer is much lower than that of the other hot-dip galvanized steel pipe, and the corrosion resistance is dozens of times that of the cold-dip galvanized steel pipe.

For the same reason, the coating of hot-dip galvanized pipes is dense, and the adhesion of the galvanized layer is better than that of cold-dip galvanized pipes. High adhesion means that the galvanized layer is not easily damaged due to impact and friction during transportation. .
When hot-dip galvanized steel pipes are made, the entire pipe is immersed in a galvanizing pool for galvanizing, so all exposed internal and external surfaces can be coated with zinc. However, cold-dip galvanized steel pipes are usually made from a single piece of zinc-plated steel pipes. Thick steel plates are rolled and welded by electric welding. There is no galvanized layer protection at the welds of the pipes. Therefore, people will choose hot-dip galvanized steel pipes which are safer and more durable.