Surface is hot-dip plated or galvanized layer welded steel pipe. Hot-dip galvanized Tube can increase the corrosion resistance of steel pipes and prolong the service life. Galvanized square tube is widely used, in addition to water,  gas, oil and other general low-pressure fluid pipeline, but also for the oil industry, especially offshore oil wells, pipeline,Pipe with the tube, as well as the bridge bridge pile, mine tunnel support frame with the tube.