Plastic-lined pipes are steel-plastic composite pipes, which are made of ordinary carbon steel pipes as the matrix and lined with thermoplastic pipes with excellent chemical stability (commonly used PE, PO, PVC, PTFE), which are formed by cold-drawing composite or rotational molding. Rotomolding is used. ?Steel lined plastic pipe rotational molding is also called rotational molding, namely rotational molding, rotational molding, rotational casting, rotational molding, etc. First, the plastic raw materials are added to the mold, and then the mold is continuously rotated along the two vertical axes and heated, so that the plastic raw materials in the mold are gradually uniformly coated and melted and adhered to the entire cavity under the action of gravity and heat energy. On the surface, it is formed into the required shape, then cooled and shaped, demolded, and finally the product is obtained. As a result, it not only has the mechanical properties of steel pipes, but also has the characteristics of plastic pipes' corrosion resistance, anti-scaling, and resistance to growth of microorganisms. It is an ideal pipeline for transporting acids, alkalis, salts, corrosive gases and other media.