Ductile iron pipe having a waterproof protective layer, and its production process

The invention discloses a ductile cast iron pipe with a waterproof protective layer and a production process thereof. The method comprises the following steps of: (1) performing surface treatment on the ductile cast iron pipe to remove surface oxides thereof; (2) spraying a zinc protective layer; (3) spraying a stainless steel protective layer; and (4) coating an enclosed corrosion-resistant protective layer. The invention has the advantages that: the zinc protective layer, the stainless steel protective layer and the enclosed corrosion-resistant protective layer are sequentially sprayed at the periphery of the ductile cast iron pipe through an arc spraying method, and a sacrificial anode protection function of the zinc protective layer, the wear resistance and corrosion resistance of thestainless steel coating and the hole-sealing corrosion inhibition performance of the enclosed coating can be cooperatively exerted, so that the ductile cast iron pipe is well protected. The ductile cast iron pipe with the coating structure has high corrosion resistance in a hydraulic environment, the waterproof protective layer has a neat appearance, covers uniformly and densely, has long protection period, high corrosion resistance and high damage resistance, secondary excavation construction is not needed, and the life cycle cost of a project is obviously reduced.