The 3LPE coating process runs on a multi-stage production line that demands a high degree of precision. How well each stage is managed directly determines the quality of the finished product.
Process Steps
- 1. Surface Preparation: The pipe surface is abrasive-blasted to remove oil and oxides, typically to a near-white metal finish (Sa 2½ per ISO 8501-1).
- 2. Preheating: The pipe is heated to a specific temperature, typically in the range of 200-230°C, to optimize adhesion of the epoxy layer.
- 3. FBE Application: An electrostatically charged epoxy powder is sprayed onto the hot pipe to form the inner layer, typically 60-100 microns thick.
- 4. Adhesive Layer: A copolymer adhesive layer is applied by extrusion to bond the epoxy to the outer polyethylene.
- 5. HDPE Outer Layer: High-density polyethylene is applied by wrapping or extrusion, bringing total coating thickness to roughly 1.8-3.7 mm depending on pipe diameter (per DIN 30670).
- 6. Cooling and Testing: The pipe is cooled, then tested for thickness, adhesion and holiday (pinhole) defects.
Why Quality Control Matters
Rigorous quality control at every stage catches potential field issues before they occur, ensuring long-term reliability for pipelines that will often be buried or submerged for decades.
