Coated steel pipe is manufactured by coating plastic based on large-diameter spiral welded pipe and high-frequency welded pipe. The maximum pipe diameter is 1200mm. Polyvinyl chloride (PVC), polyethylene (PE), epoxy can be coated depending on different needs. Resin (EPOZY) and other plastic coatings with different properties, good adhesion, strong corrosion-resistance, resistant to strong acids, strong alkalis and other chemical corrosion, non-toxic, non-corrosive, wear-resistant, impact-resistant, and strong penetration resistance, The surface of the pipeline is smooth and does not adhere to any substance, which can reduce the resistance during transportation, increase the flow rate and transportation efficiency, and reduce the pressure loss of transportation. There is no solvent and no exudate substance in the coating, so it will not pollute the conveyed medium, to ensure the purity and sanitation of the fluid. It can be used alternately with cold and hot cycles in the range of -40℃ to +80℃, without aging, It does not crack, so it can be used in harsh environments such as cold regions.