Introduction to Common Anti-Corrosion Coatings for Steel Pipes
1. Polyethylene (3PE) Anti-Corrosion Coating for Steel Pipes:
The structural composition of the polyethylene anti-corrosion coating includes: a fusion-bonded epoxy powder coating, a polymer adhesive intermediate layer, and an outer polyethylene protective layer. Epoxy powder is a thermosetting, non-toxic coating that forms a high molecular weight cross-linked structure after curing, offering good chemical anti-corrosion properties and high physical mechanical performance.
The outer wall coating of steel pipes with polyethylene (3PE) is primarily used for anti-corrosion on the outer walls of steel pipes transporting fluids such as petroleum, natural gas, chemical raw materials, and urban water supply. Its anti-corrosion process and product performance fully comply with the requirements of domestic and international standards, including SY/T0413-2016 "Technical Standard for Polyethylene Anti-Corrosion Coating of Buried Steel Pipes," GB/T23257-2017 "Polyethylene Anti-Corrosion Coating for Buried Steel Pipes," and DIN30670 German "Technical Standard for Polyethylene Anti-Corrosion Coating of Buried Steel Pipes."
The function of the epoxy primer layer is to form a continuous film, providing good adhesion through bonding and curing with the steel pipe surface, along with excellent chemical resistance and cathodic disbondment resistance.
The role of the polymer adhesive is to fuse with the epoxy powder before it gels and bond with the outer polyethylene layer, integrating the three layers into a whole.
The polyethylene (3PE) anti-corrosion coating offers high anti-corrosion performance and physical mechanical properties. Factory prefabrication allows for fast production speeds and continuous automated manufacturing. The operation is simple, the process is mature, and it is suitable for long-term, high-volume production by professional anti-corrosion companies.
2. Single-Layer and Double-Layer Fusion-Bonded Epoxy (FBE) Powder Outer Coating:
The single-layer fusion-bonded epoxy powder (FBE) coating on the inner wall of steel pipes is mainly applicable for anti-corrosion coatings on the inner walls of steel pipes transporting fluids such as petroleum, natural gas, chemical raw materials, and water. Its anti-corrosion production process and product performance fully comply with the requirements of domestic and international technical standards, including SY/T0315-2013 "Technical Standard for Fusion-Bonded Epoxy Powder Outer Coating of Steel Pipes," SY/T0442-2010 "Technical Standard for Fusion-Bonded Epoxy Powder Inner Anti-Corrosion Coating of Steel Pipes," and DIN30678 German "Technical Standard for Fusion-Bonded Epoxy Powder Outer Coating of Steel Pipes."
The fusion-bonded epoxy powder (FBE) coating offers superior corrosion resistance, abrasion resistance, and environmental hygiene indicators compared to other coatings, and is widely used in the drinking water sector.
The double-layer fusion-bonded epoxy powder coating is developed from the single-layer fusion-bonded epoxy powder coating, enhancing the physical mechanical properties of the outer epoxy powder coating.
Single-layer and double-layer fusion-bonded epoxy powder (FBE) outer coatings offer high anti-corrosion performance and physical mechanical properties. Factory prefabrication allows for fast production speeds and continuous automated manufacturing. The operation is simple, energy consumption is low, the process flow is short, and the investment scale is small, making it suitable for long-term, high-volume production by professional anti-corrosion companies.
3. Spray-Coated Polyethylene Powder Anti-Corrosion Coating
The spray-coated polyethylene powder outer coating uses steel pipes as the base material. After heating the steel pipe to 250 to 260°C, a molten coating is formed on the pipe surface by spray or dip coating. The thickness of the spray-coated polyethylene powder outer coating is 1.8mm. The spray-coated polyethylene coating fully complies with CJ/T120-2016 "Plastic-Coated Composite Steel Pipes for Water Supply." Due to the characteristics of the production process and limitations of production equipment, the peel strength of this coating is far inferior to the aforementioned anti-corrosion coatings. Currently, plastic-coated composite steel pipes for water supply are mainly used in water supply and drainage projects.
Currently, the production efficiency of spray-coated polyethylene powder outer coatings is not high. Heating large-diameter steel pipes uniformly is difficult, the coating thickness is not easily controlled, and the PE powder recovery efficiency is low.