Production Process of Polyethylene (PE) Coated Anti-Corrosion Steel Pipes

Outer polyethylene (PE) coated anti-corrosion steel pipe is a widely used anti-corrosion pipeline product in buried oil and gas transmission, water supply, and municipal engineering. It combines the high mechanical strength of the steel pipe with the excellent chemical resistance, impact resistance, and waterproof performance of polyethylene, forming a high-performance protective barrier for the pipe. The production process of the outer PE coating directly determines the anti-corrosion effect and service life of the pipeline, making it a key factor when choosing a reliable supplier.

1.Steel Pipe Surface Pretreatment

The first and most critical step in the production process is the pretreatment of the steel pipe surface. The pipe is first degreased to remove oil, grease, and other surface contaminants. Then, it undergoes shot blasting or sandblasting to eliminate rust, scale, welding slag, and debris, achieving a near-white metal finish (typically Sa2.5 standard) with controlled surface roughness. This ensures strong mechanical adhesion between the subsequent coating layers and the steel pipe substrate.

2.Preheating and Primer Application

After pretreatment, the steel pipe is preheated to a specific temperature using an induction heating system. The preheating temperature is precisely controlled between 180°C and 220°C. Immediately after preheating, a thin layer of epoxy powder (FBE) is electrostatically sprayed onto the pipe surface. This epoxy primer cures to form a corrosion-resistant base layer, which is essential for the long-term performance of the coating system.

3. Adhesive and Polyethylene (PE) Coating Application

The core step of the process is the application of the adhesive and polyethylene layers. A copolymer adhesive is co-extruded with the polyethylene layer onto the rotating steel pipe. The adhesive layer bonds the epoxy primer to the outer polyethylene layer, ensuring strong interlayer adhesion. The outer layer is made of high-density polyethylene (HDPE), which is continuously extruded and wrapped around the pipe to form a uniform, seamless protective layer. The thickness of the PE coating is carefully controlled according to project requirements, typically ranging from 1.8mm to 3.7mm.

4. Cooling and Solidification

After the coating process, the pipe is immediately passed through a water spray cooling line. The controlled cooling allows the polyethylene to solidify gradually, preventing thermal stress and ensuring the coating remains smooth, wrinkle-free, and firmly bonded to the pipe surface.

5. Finishing and Quality Inspection

After cooling, the pipe ends are trimmed, and any excess coating is removed. Protective caps are installed to prevent damage to the coating during transportation. Every finished pipe undergoes comprehensive quality control tests before delivery:

Only pipes that pass all inspections are marked with specifications, batch numbers, and certification marks, then packaged for delivery. With mature production technology and strict quality control, outer polyethylene coated steel pipe provides a reliable, long-lasting anti-corrosion solution for pipeline infrastructure projects worldwide.