Three-layer polyethylene (TEPE) anti-corrosion coating is currently the mainstream external anti-corrosion solution for buried oil and gas pipelines, boasting the longest service life (≥50 years). It consists of three layers: an epoxy powder layer, an adhesive layer, and a high-density polyethylene (HDPE) layer.
I. Three-layer Structure (from inside to outside)
Bottom Layer: Fusion-bonded epoxy powder layer (FBE)
Thickness: ≥100μm (commonly 120–150μm)
Function: Forms a chemical bond with the steel pipe, providing extremely strong adhesion; resistant to chemical corrosion and cathodic disbondment, forming the "foundation" of anti-corrosion.
Process: Heating the steel pipe to 190–200℃, electrostatically spraying, and then curing.
Middle Layer: Copolymer Adhesive (AD)
Thickness: 170–250μm
Material: Maleic anhydride-grafted polyethylene (PE-g-MA) or EAA copolymer
Function: "Molecular bridge"-one side reacts with epoxy resin, the other side melts with polyethylene, preventing delamination and absorbing temperature/soil stress.
Outer layer: High-density polyethylene (HDPE)
Thickness: 1.8–3.7 mm (depending on pipe diameter)
Function: Mechanical protection-impact resistance, scratch resistance, soil stress resistance/protection of plant roots; extremely low water permeability, blocking water, oxygen, acids, alkalis, and salts.
Process: Extrusion winding or coating, temperature 220–230℃.
