1. Professional Protection, Worry-Free Corrosion Prevention

Corrosion is a phenomenon where materials (mainly metals) undergo chemical or electrochemical reactions with the surrounding environment, leading to performance degradation. In the fields of construction, industry, and marine engineering, corrosion prevention has always been a crucial topic. Whether it is towering steel structures or deep-sea marine facilities, corrosion issues can become sources of safety hazards.

The international standard ISO 12944 is the most commonly used corrosion protection grade standard, widely applied in the protective design of steel structures, industrial equipment enclosures, and outdoor equipment.

2. Classification of Corrosion Protection Grades

The international standard ISO 12944-2 provides comprehensive classification and guidance for corrosion protection coating systems of steel structures. According to environmental corrosivity, atmospheric environments are divided into six levels from C1 (low corrosivity) to CX (extremely high corrosivity):

3. Detailed Explanation of Each Corrosion Protection Environment Level

1. C1 Level (Low Corrosivity)

• Typical Environment Rural or clean urban environments with no pollution.

Coating Selection Generally no corrosion protection coating or simple decorative coatings are sufficient.

 

2. C2 Level (Low Corrosivity)

• Typical Environment Urban environments with light pollution.

Coating Selection ：

• Single-layer primer plus ordinary topcoat, such as epoxy primer + acrylic topcoat.

 

3. C3 Level (Medium Corrosivity)

• Typical Environment Urban industrial environments or coastal areas with moderate pollution.

Coating Selection ：

• Three-layer coating system (primer, intermediate coat, topcoat).

• For example: zinc-rich primer (40~80 μm) + epoxy intermediate coat (80~160 μm) + polyurethane topcoat (40~80 μm).

 

4. C4 Level (High Corrosivity)

• Typical Environment Industrial environments or coastal areas with high humidity and heavy pollution.

Coating Selection ：

• Epoxy zinc-rich primer (50~80 μm)

• Epoxy micaceous iron oxide intermediate coat (100~240 μm)

• Polyurethane topcoat (50~80 μm)

• Total dry film thickness Not less than 200 μm

 

5. C5 Level (High Corrosivity)

• Typical Environment High humidity, heavily polluted industrial areas, marine environments such as coastal chemical plants, ports, and mining equipment.

Coating Selection ：

• Epoxy zinc-rich primer (50~80 μm)

• Epoxy micaceous iron oxide intermediate coat (160~360 μm)

• Polyurethane/fluorocarbon topcoat (50~80 μm)

• Total dry film thickness Not less than 260 μm.

 

6. CX Level (Extreme Corrosivity)

• Typical Environment Extreme corrosive environments in coastal areas, offshore drilling platforms, ship hulls immersed in seawater, or chemical corrosion environments.

Coating System ：

• Primer Zinc-rich primer or zinc chromate primer (75 ~ 100 μm), providing sacrificial anode protection.

• Intermediate Coat Epoxy thick-film coating (180 ~ 400 μm), increasing barrier layer thickness.

• Topcoat Fluorocarbon or polyurethane coating (50 ~ 80 μm), providing UV resistance and weatherability.

 

 

4. Scientific Principles of Coatings

1. Barrier Effect Coating materials block moisture, oxygen, and corrosive ions.

2. Cathodic Protection Zinc-rich coatings form an electrochemical barrier, sacrificing zinc to protect steel.

3. Adhesion Surface treatment quality directly affects coating lifespan; sandblasting to Sa 2.5 standard is the best choice.

5. Summary

The core of corrosion prevention lies in "scientific matching" and "standardized construction." On one hand, it is necessary to reasonably match primers, intermediate coats, and topcoats according to different corrosive environments to build a layered protection system that specifically resists salt spray, acids and alkalis, ultraviolet rays, and other corrosions; on the other hand, strictly control the construction process—from substrate rust removal, roughness treatment, to coating thickness control and interlayer drying intervals—to ensure each step meets standards. Through professional testing and subsequent maintenance, the long-term effectiveness of corrosion protection is guaranteed. The synergy of both aspects achieves the best protection.