This dual-layer epoxy powder coating is formulated using multiple types of epoxy resins and functional curing agents. The base layer, like other epoxy anti-corrosion coatings, offers excellent corrosion resistance. The outer layer not only maintains corrosion protection but also enhances the protective properties, making it suitable for highly demanding anti-corrosion environments, especially for pipelines crossing mountainous areas, rivers, and hilly regions.
Excellent adhesion between the base layer and the substrate, as well as between the epoxy layers.
Strong resistance to permeation and corrosion.
The outer layer has high hardness and density, is scratch-resistant, and provides good resistance to plant root penetration.
The coating has excellent resistance to high-temperature cathodic disbondment.
| Item | Quality Indicator | Test Method |
|---|---|---|
| Appearance | Uniform color, no lumps | Visual inspection |
| Volatile Content (%) | ≤ 0.6 | Q/CNPC 38-2002 Appendix B |
| Curing Time (230°C) (min) | ≤ 3 | SY/T 0315-2005 |
| Magnetic Substance Content (%) | ≤ 0.002 | GB/T 6570 |
| No. | Test Item | Technical Indicator | Test Method |
|---|---|---|---|
| 1 | Appearance | Smooth, uniform color, no bubbles, cracks; slight orange peel allowed | Visual inspection |
| 2 | Adhesion (Grade) (24h or 48h) | 1-2 | SY/T 0315-2005 |
| 3 | Cathodic Disbondment Resistance (24h or 48h) (mm) | ≤ 6 | SY/T 0315-2005 |
| Cathodic Disbondment Resistance (28d) (mm) | ≤ 8 | SY/T 0315-2005 | |
| Cross-Section Porosity of Base Layer | 1-4 | SY/T 0315-2005 | |
| Bonding Surface Porosity of Base Layer | 1-4 | SY/T 0315-2005 | |
| 4 | Flexibility (2°) (0° or -30°) (Ordinary Grade) | No cracks | Q/CNPC 38-2002 Appendix D |
| Flexibility (1.5°) (0° or -30°) (Enhanced Grade) | No cracks | Q/CNPC 38-2002 Appendix D | |
| Impact Resistance (10J) (Ordinary Grade) | No pinholes | Q/CNPC 38-2002 Appendix E | |
| Impact Resistance (15J) (Enhanced Grade) | No pinholes | Q/CNPC 38-2002 Appendix E | |
| Scratch Resistance (30Kg) (Ordinary Grade) | Scratch depth ≤ 350 µm, no leakage | Q/CNPC 38-2002 Appendix F | |
| 8 | Scratch Resistance (50Kg) (Enhanced Grade) | Scratch depth ≤ 500 µm, no leakage | Q/CNPC 38-2002 Appendix F |
Q/CNPC 38-2002
Complex anti-corrosion environments, especially pipelines crossing mountainous areas, rivers, and hilly regions.
Electrostatic spraying.
The steel pipe surface should be free of oil and moisture; the surface treatment quality should reach Sa2 1/2 level (GB/T 8923); the anchor pattern depth should be 50-90 mm; dust and abrasives on the steel pipe surface should be blown clean.
The product should be stored in a well-ventilated, dry indoor environment with a temperature below 30°C, away from heat sources, corrosive chemicals, and chemical solvents, and protected from strong light exposure; the stacking height should not exceed four layers; avoid long-term pressure, ensure the packaging box is sealed to prevent caking and moisture, which can affect fluidization performance.
Powder coatings can be categorized by resin system (epoxy, polyester, hybrid, polyurethane), appearance (smooth, texture, hammer, metallic, pearlescent), or performance level (anti-corrosion, heat-resistant, UV-resistant, architectural grade, automotive grade).
Powder coatings offer thousands of colors in gloss, matte, satin, metallic, candy, texture, wrinkle, hammer tone, wood grain, fluorescent, and other custom effects. Special powders can create soft-touch, anti-scratch, anti-fingerprint, or anti-graffiti surfaces.
The process generally includes surface pretreatment (degreasing, phosphating, chromating, sandblasting), drying, electrostatic spraying, curing in an oven, and cooling. A well-controlled pretreatment and curing process ensures strong adhesion and long service life.
Powder coatings are environmentally friendly, solvent-free, and produce minimal waste. They offer excellent corrosion resistance, weather durability, mechanical strength, and uniform film appearance. The coating is tough, impact-resistant, scratch-resistant, and has a long lifespan.
Powder coatings are widely used in appliances, aluminum profiles, architectural components, automotive parts, bicycles, furniture, outdoor equipment, machinery, electrical cabinets, pipeline systems, and general industrial and consumer goods.
Powder coating is a dry finishing technology where finely ground powder is electrostatically sprayed onto a metal or non-metal surface and then cured at high temperature. After curing, the powder melts into a continuous, durable, and decorative coating layer.
Powder coating protects the substrate from corrosion, weathering, chemical attack, and mechanical wear. It also provides decorative appearance with rich colors, gloss levels, textures, and special effects.
In many industrial applications, powder coating outperforms liquid paint. It forms a thicker and tougher coating, resists corrosion and chemicals better, and does not contain VOCs. It also provides excellent consistency and cost-effective mass production.
It is called powder coating because the coating material is a solid powder instead of a liquid paint. The coating is formed by melting and curing powder particles under heat.
Powder coatings include several families depending on resin chemistry:
• Epoxy powders
• Polyester powders
• Epoxy-polyester hybrid powders
• Polyurethane powders
• Acrylic powders
• Fluorocarbon (PVDF) powders
Each type has its own performance features such as corrosion resistance, UV resistance, chemical resistance, outdoor durability, or decorative properties.
Powder coatings are based on thermoset or thermoplastic resins combined with pigments, curing agents, fillers, additives, and in some cases metallic or effect particles. Common substrates include steel, aluminum, galvanized metal, MDF, and certain heat-resistant plastics.
The lifespan depends on powder type, film thickness, application method, pretreatment, and service environment. Indoor coatings can last more than 10–20 years. High-grade outdoor polyester or fluorocarbon powders can last 15–25 years or longer under UV exposure.
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