Hot galvanized    products are made of steel pipes which are pickled with acid to remove the ferric oxide, and then the steel pipes are dried and dipped into a melted zinc pot, the melted zinc is blown onto the internal and external surfaces of the pipes to form a layer of zinc, which is purified at last . the water supply pipelines, sewage pipes, fire fighting pipes , gas pipelines, cold and heat supply pipelines, compressed air pipes, and used in water supply projects, conduit pipes in telecommunication, electric and building industry.