Corrosion categories acc. ISO 12944-5
Be aware that your steel is to be addressed to the correct corrosion category
It is requirement to life span in a concrete environment that determines the choice of the corrosion category a given steel structure to be treated for.
Steel structures must be used/placed under different climatic conditions:
- Low corrosion categories of protected environments such as indoor use
- High corrosion categories of vulnerable and coastal surroundings
Corrosion categories are divided into 6 different categories according to ISO 12944-5, by their scope:
| Category | Outdoor | Indoor |
| C1: Very low | Heated buildings with production, such as offices, shops, schools, hotels, etc. | |
| C2: Low | Environments with low levels of polution. Mainly rural setting | Unheated buildings where condensation can occur For example, warehouses, depots, sport facilities and similar. |
| C3: Medium | City and industrial environments with moderate sulfur dioxide pollution. Coastal areas with low salinity | Production areas with high humidity and some air pollution. For example, industrial plants, laundries, breweries, food production, etc. |
| C4: High | Industrial areas and coastal areas with moderate salinity | Chemical industry, ship- and boat yard. |
| C5I: Very high | Industrial areas with high humidity and aggressive environment | Buildings and areas with almost permanent condensation and with high pollution impact. |
| C5M: Maritime | Coastal environment and off-shore installations with high salt content | Buildings and areas with a high degree of condensation and with high impact of pollution. |