The three-layer polyethylene anticorrosive coating is referred to as 3PE for short, the bottom layer is epoxy powder coating, and the middle layer is adhesive, which is polyethylene. The first layer of 3PE is epoxy coating, the second layer is adhesive and the third layer is extruded polyethylene. The layers are closely combined to form a composite structure, which complements each other. Using the strong adhesion between epoxy powder and steel pipe surface to improve the adhesion; Using the excellent mechanical strength, chemical stability, insulation, plant root penetration resistance and water penetration resistance of extruded polyethylene to improve its comprehensive performance, the comprehensive performance of the three-layer PE anticorrosive coating is more prominent and comprehensive, and it is suitable for harsh environments with high requirements on the mechanical properties, soil compression resistance and water resistance of the covering layer, such as gravel soil, stone road sections, areas with high soil water content and developed plant roots. Before coating the anticorrosive coating, remove the grease, dirt and other attachments on the steel pipe surface, and pretreat the steel pipe surface after preheating. The preheating temperature of steel pipe is 40~60℃. The quality of surface pretreatment shall meet the requirements of Sa2.5 in GB/T8923 "Rust Grade and Derusting Grade of Steel Surface before Painting", and the depth of anchor line shall reach 50μ m ~ 75μ m The welding slag and burr on the steel pipe surface shall be removed.
The surface layer of polyethylene is made of medium-high density polyethylene (poly is used overseas), so the three-layer anti-corrosion structure combines the adhesion and corrosion resistance of epoxy powder with the weather resistance and mechanical damage resistance of polyethylene layer, making up for their respective shortcomings, thus greatly improving the service life of the coating. The function of the middle layer of polymer adhesive is to fuse with epoxy powder coating before gluing, and to bond with the outer polyethylene layer to make the three layers become a whole. The appearance is bright and transparent fisheye-like uniform particles, which is a new patented technology and process in China. Excellent compatibility with various polyethylene materials and epoxy powder. The function of molten epoxy powder at the bottom layer is to form a continuous coating film, which is bonded and solidified with the surface of steel pipe, providing good adhesion, chemical resistance and cathodic stripping resistance.