Steel Corrosion Protection: Systems, Durability & How Not to Waste Money
Corrosion doesn't forgive — but the right AKZ system provides 30-50+ years of protection. Here's how to choose the system by corrosion category without overpaying.
Steel is an excellent material — load-bearing, economical, recyclable. But it has one weakness: corrosion. Without proper anti-corrosion protection (AKZ), a steel structure can lose its load-bearing capacity in just 10-15 years. With the right system: 50+ years without intervention.
Here's how to choose the right AKZ — and not waste money on too little or too much.
Step 1: Determine the corrosion category
Corrosion Categories (EN ISO 12944)
The environmental category determines how aggressive corrosion is at your building's location. This determines which protection system you need — and how thick the layer.
3 main AKZ systems
1. Coating system (paint)
Primer + intermediate coat + topcoat. Applied by brush, roller, or spray. Cheapest initially, but requires renewal every 10-15 years. Ideal for interiors (C1-C2) and non-exposed elements.
2. Hot-dip galvanizing
Immersion of steel elements in molten zinc at 450°C. Layer thickness 85-120 µm per EN ISO 1461. Maintenance-free for 25-40 years, even in C3-C4 conditions. Our recommendation for 90% of structures.
3. Duplex system (galvanizing + coating)
Combination of hot-dip galvanizing and coating system. Synergistic effect: duplex system durability is 1.5-2× longer than the sum of individual systems. For C4-C5 categories, bridges, coastal structures.
Expected AKZ System Durability
Cost comparison over 50 years
| System | Initial (€/m²) | Renewal | Total cost 50 yrs | Recommendation |
|---|---|---|---|---|
| Coating | 15-25 | Every 10-15 yrs | ◆◆◆◆ High | C1-C2 |
| Hot-dip galvanizing | 25-40 | None (25-40 yrs) | ◆◆ Medium | C2-C4 |
| Duplex | 40-60 | None (40-60 yrs) | ◆ Lowest long-term | C3-C5 |