The process of manufacturing large-diameter EP epoxy resin coated steel pipes for water supply and drainage mainly includes steps such as steel pipe pretreatment, plastic coating, and curing. The pre-treatment of steel pipes is a crucial step, which requires removing impurities such as oil stains and rust from the surface of the pipes to ensure a tight fit between the plastic layer and the pipes. The coating of plastic layers generally adopts the methods of melt spraying or immersion coating, and commonly used plastic materials include polyethylene, polypropylene, epoxy resin, etc