Prepainted Galvanized Steel Sheets: High-Performance Coated Metal for Industrial & Architectural Applications
What is Prepainted Galvanized Steel?
Prepainted galvanized steel sheets are zinc-coated substrates (60-275g/m²) with factory-applied paint systems, combining corrosion resistance with aesthetic versatility. Manufactured via continuous hot-dip galvanizing (HDG) or electrogalvanizing (EG) processes, these sheets feature PVDF, polyester, or silicone-modified coatings in 30+ RAL colors. Ideal for roofing, appliances, and automotive parts, they deliver 15-25 years service life at 40% lower cost than stainless steel alternatives.
Key Advantages
1️⃣ Dual-Layer Protection
- Base Layer: Zinc coating (Z80-Z275) prevents substrate corrosion
- Top Layer: 20-30μm polymer coating resists UV/chemical degradation
2️⃣ Precision Manufacturing
- Thickness tolerance: ±0.02mm (0.12-6mm range)
- Automated edge trimming (600-1500mm width)
3️⃣ Sustainable Solution
- 85% recycled steel content
- REACH-compliant coatings (VOC <50g/L)
Technical Specifications
1. Material Grades & Standards
| Grade (EN 10346) | Coating Type | Yield Strength | Paint Adhesion |
|---|---|---|---|
| DX51D+Z | HDG + Polyester | 140-260 MPa | Class 1 (ISO 2409) |
| S350GD+Z | HDG + PVDF | 350 MPa | Class 0 (No peel) |
| SGCC (JIS G3302) | EG + SMP | 220 MPa | Class 2 |
PVDF Coating Performance: 40% gloss retention after 10,000hr QUV test
2. Critical Dimensions
- Thickness: 0.3mm (lightweight cladding) to 6mm (structural panels)
- Corrugation Types:
- Wave Height: 15-50mm (AS 1397 compliant)
- Pitch: 75-200mm
Production Process
- Continuous Galvanizing Line (CGL)
- Zinc bath temperature: 460°C ±5°C
- Coating control: Air knife system (±3g/m² accuracy)
- Coating Stage
- Primer: Chromate conversion coating (1-3μm)
- Topcoat: 2-coat wet-on-wet application (15μm+25μm)
- Curing
- Oven temperature: 220-250°C (PMT)
- Line speed: 80-120m/min
Performance Comparison
| Parameter | Prepainted HDG | Electrogalvanized | Aluminum |
|---|---|---|---|
| Salt Spray Resistance | 1,500hrs | 500hrs | 300hrs |
| Thermal Conductivity | 50 W/mK | 50 W/mK | 237 W/mK |
| Cost/m² (0.5mm) | $12.8 | $9.5 | $28.7 |
Application Guide
Architectural
- Roofing: SMP-coated Z275 sheets (50-year color warranty)
- Facades: PVDF-coated Z180 (meets AAMA 2605 standard)
Industrial
- Appliance Housings: EG-coated DX53D (deep-drawing capability)
- Automotive: HDG S550GD (HSLA grade for structural parts)
Quality Assurance
- Coating Tests:
- Cross-cut adhesion (ASTM D3359)
- T-bend flexibility (ASTM D4145)
- Certifications:
- ISO 9001:2015
- LEED v4.1 MR Credit
Installation Best Practices
- Storage: Stack vertically with PE separators
- Cutting: Laser/plasma preferred (debris-free edges)
- Fastening: Stainless steel screws with EPDM washers
Environmental Impact
Our production achieves 35% energy reduction through:
- Regenerative thermal oxidizers (95% VOC destruction)
- Closed-loop water cooling systems
Why Choose Prepainted Sheets?
- Custom Solutions: Available in camouflage/woodgrain patterns
- Global Compliance: Meets ASTM A755 (US), GB/T 12754 (CN), KS D3506 (KR)
- Fast Turnaround: 10-day production lead time for standard colors
Industry Fact: Over 70% of modern warehouse roofs in Southeast Asia use prepainted Z275 sheets for typhoon resistance (up to 200km/h wind rating).
For projects requiring enhanced fire resistance, specify our A2-s1,d0 fire-rated sheets meeting EN 13501-1 standards.
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