Corrosivity Categories (ISO 9223)
ISO 9223 classifies how aggressive an environment is to metals, guiding coating selection.
| Category | Corrosivity | Typical environment |
|---|---|---|
| C1 | Very low | Heated indoor, dry |
| C2 | Low | Rural, low pollution |
| C3 | Medium | Urban, moderate industrial |
| C4 | High | Industrial, moderate coastal |
| C5 | Very high | Aggressive industrial / coastal |
Higher categories favour thicker or self-healing coatings (HDGI, ZAM). Match coating to the site category.
Frequently asked questions
- Which coating suits a C5 environment?
- Aggressive C5 industrial/coastal sites favour hot-dip galvanising (HDGI) or ZAM.
Related resources
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