The core functions of coating:
1. Corrosion prevention: Steel is a metal prone to rust. Coating isolates steel from water, air, and chemicals, preventing it from easily rusting.
2. Enhanced weather resistance: When steel plates are exposed to sunlight, rain, sea breezes, etc., the coating can prevent fading, chalking, or corrosion.
3. Aesthetics: Coatings can be colored, enhancing the appearance. Examples include factory exterior wall panel and roof panels.
Such as Fire Resistance Rock Wool Mineral Wool Sandwich Panel
How does the steel sheet coating affect the corrosion resistance of sandwich panels
01
Metallic coating = first line of defense
Metallic coating = first line of defense
The base steel is usually protected by a metallic coating such as galvanized zinc (Z coating) or aluminum-zinc alloy (AZ coating).
For example:
• Z100 / Z180 / Z275
• AZ50 / AZ100 / AZ150
The higher the coating mass, the better the corrosion protection.
Especially in humid or coastal environments, AZ150 or more often performs significantly better than standard galvanized steel.
02
Paint coating = environmental barrier
The top paint layer plays a major role in preventing moisture, salt spray, UV exposure, and chemical gases from reaching the metal surface.
Common options include:
• PE – economical for standard warehouse use
• SMP/ HDP– improved weather resistance
• PVDF – excellent UV and corrosion resistance
Different projects require different coating systems..
Warehouse / Factory
External metal sheet: AZ100/AZ150 + PE
Coastal building
External metal sheet:AZ150 + PVDF
Poultry farm / Chemical workshop
Internal metal sheet:AZ150 + PVDF or according projects' requirement
Another important point in coating selection is the quality and transparency of the steel coil supplier.
In the market, there are many small or unbranded manufacturers who only mention terms like PE coating, PVDF coating, or simply galvanized steel, without clearly specifying the zinc coating mass (such as Z100 / Z150 / AZ150) or the paint thickness.
Without these key parameters, it is difficult to truly evaluate the corrosion resistance and service life of the panel.
At Duowei, in order to ensure stable quality, we insist on sourcing raw materials only from well-known Chinese steel coil manufacturers with recognized overseas certifications.
For our standard coating systems:
• PE top coat: 20 μm
• HDP / SMP top coat: 23 μm
• PVDF top coat: 25 μm
• Back coat: epoxy paint, 5–7 μm
We believe that clear specifications and reliable raw material sourcing are the foundation of long-term panel performance
Choosing the right coating is not just about appearance - it is about durability, maintenance cost, and long-term project value.
If any concerns about the coating or panel selection, please choose Duowei.
Founded in 1983, Duowei is a leading provider of green industrial building envelope systems.
Duowei has 5 sandwich panel factories in China, located in Tianjin, Nantong, Shenyang, Guangdong, and Sichuan. We have also established overseas companies in major markets such as Southeast Asia, Africa, and South America, serving more than 15,000 customers. Our products have been exported to over 100 countries and regions worldwide.
We are certified with FM Approval (USA), BomBa certification (Malaysia), CE certification (EU), and QAI certification (Canada).
Quality assurance and customer satisfaction have always been our constant pursuit.
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