ISO 12944 C5 Very High Corrosion Coating System
For very high humidity, aggressive industrial atmospheres, and severe coastal or marine exposure.
Applicable Standards
Environment Definition
ISO 12944 C5 represents very high atmospheric corrosivity. It is used for severe coastal and marine atmospheres, aggressive industrial areas, and high-humidity environments where corrosion pressure is significantly higher than normal urban exposure.
Typical examples include coastal infrastructure, port steelwork, chemical plant structures, pulp and paper mills, offshore-adjacent facilities, and exposed industrial assets with demanding maintenance requirements.
Coating Selection Logic
C5 systems need careful technical review rather than a generic product recommendation. The system normally relies on excellent surface preparation, zinc-rich or inorganic zinc primer options, high-build epoxy barrier coats, and a durable exterior topcoat.
If the steel is exposed to immersion, tidal splash, buried service, or concentrated chemicals, evaluate CX or a dedicated immersion/chemical-resistance system.
Starting System Pattern
| Layer | Typical role | Notes |
|---|---|---|
| Surface preparation | Abrasive blasting with tight cleanliness control | Confirm Sa grade, profile, edge preparation, dust, oil, and salt contamination limits. |
| Primer | Inorganic zinc, epoxy zinc-rich, or approved high-performance primer | Confirm zinc content claims and compatibility with the next coat. |
| Intermediate | High-build epoxy MIO or other barrier layer | Often the main contributor to protective film build. |
| Topcoat | Fluorocarbon, aliphatic polyurethane, polysiloxane, or specialty topcoat | Select according to UV, color retention, chemical atmosphere, and maintenance plan. |
Technical Review Points
- Confirm whether the environment is marine atmosphere, industrial atmosphere, or a mixed coastal/industrial case.
- Define expected durability and inspection interval before choosing film build.
- Review edge retention, welds, bolts, and field repair details.
- Confirm current Qilu Paints TDS/SDS and destination-market documentation before specification.
Related Qilu Paints Products
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