Corrosion is the number one field-failure mode for outdoor heat pump enclosures. The choice between galvanized steel and powder-coated steel — and the quality of each — determines whether your units still look and function properly after five winters in the rain.
Three Common Approaches
| Option | Typical Use | Cost | Corrosion Life (Outdoor) |
|---|---|---|---|
| Electro-galvanized (SECC) + clear coat | Indoor / sheltered units | Low | 3–5 years |
| Hot-dip galvanized (SGCC) | Utility / agricultural outdoor gear | Medium | 8–15+ years |
| Galvanized + powder coating (duplex) | Premium heat pumps, coastal markets | Medium-high | 15–25 years |
Why Duplex Systems Win for Heat Pumps
The best of both worlds: zinc provides cathodic protection at scratches and cut edges, while the powder coat adds color, UV stability and a barrier against salt and moisture. The combination lasts significantly longer than either system alone — the so-called duplex effect.
Quality Traps to Avoid
- Cut edges uncoated: laser-cut edges expose bare steel. Specify edge sealing or ensure the zinc layer is thick enough to protect edges sacrificially.
- Powder too thin: less than 60 µm film thickness gives poor coverage over sharp corners. We target 60–100 µm with pre-treatment (degrease + zinc phosphate).
- White rust: freshly galvanized surfaces stored in humid conditions develop white corrosion. Proper passivation and dry storage prevent this.
What Fulei Metal Does
We offer electro-galvanized (SECC), hot-dip galvanized (SGCC) and full duplex systems: zinc-plated base steel, pre-treatment, and polyester powder coating in any RAL color, verified with coating thickness meters and salt-spray testing per ISO 9227. Tell us your market and expected service life, and we will specify the right system for your budget.