ASTM Standard PPGL Roofing Sheet: High-Performance Al-Zn Alloy Protection
Our ASTM Standard PPGL (Prepainted Galvalume) Roofing Sheets are engineered for premium architectural projects that demand long-term structural integrity and superior thermal efficiency. Combining the sacrificial protection of zinc with the barrier protection of aluminum, these color-coated panels are compliant with ASTM A792 (for the substrate) and ASTM A755 (for the coating system), making them the gold standard for roofing in coastal, industrial, and high-heat environments.
The Galvalume Advantage: 55% Al-Zn Alloy Substrate
The core of our PPGL roofing sheet is a 55% Aluminum, 43.4% Zinc, and 1.6% Silicon alloy coating. This specific composition, governed by ASTM A792, offers:
Twice the Longevity: Galvalume substrates typically last 2 to 4 times longer than traditional galvanized steel (PPGI) in the same environment.
Superior Heat Reflection: The aluminum content provides high thermal reflectivity, keeping buildings cooler and significantly reducing energy costs for air conditioning.
Self-Healing Properties: The zinc component provides essential cathodic protection at cut edges and scratches, preventing the spread of rust.
Key Benefits for Architectural Applications
Lightweight & High Strength: The ASTM compliant steel core allows for thinner gauges without compromising snow or wind load capacities, reducing the overall weight of the roof structure.
Aesthetic Versatility: Available in a wide spectrum of RAL colors and diverse profiles (Circular, Trapezoidal, or IBR), providing architects with unlimited design flexibility.
Environmental Sustainability: Our PPGL sheets are 100% recyclable and feature “Cool Roof” pigments that mitigate the Urban Heat Island effect.
Technical Specifications Summary (ASTM Compliance)
| Feature | ASTM Standard Requirement | Bomis Steel Performance |
| Substrate Grade | ASTM A792 (CS / SS Grade 33-80) | Prime Quality Full Hard / Soft |
| Al-Zn Coating | AZ50, AZ100, AZ150 | Precise Alloy Control |
| Paint Coating | ASTM A755 (PVDF / SMP / PE) | High UV & Chalk Resistance |
| T-Bend Test | $\leq$ 2T (No Cracking) | Guaranteed Adhesion |
| Pencil Hardness | $\geq$ H | Superior Surface Durability |
| Heat Resistance | Up to 315°C | No Discoloration |
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Frequently Asked Questions
1. What is the main difference between PPGI and PPGL roofing sheets?
The primary difference lies in the substrate coating. PPGI (Prepainted Galvanized) uses a 100% zinc coating, while PPGL (Prepainted Galvalume) uses a 55% Aluminum-Zinc alloy coating. According to ASTM A792 standards, the aluminum in PPGL provides superior barrier protection and heat reflectivity, making PPGL last 2 to 4 times longer than PPGI in highly corrosive or coastal environments.
2. How does the ASTM A792 standard ensure the quality of PPGL?
ASTM A792/A792M is the standard specification for 55% Al-Zn alloy-coated steel. It governs the chemical composition of the coating, the mechanical properties of the steel base, and the coating weight (such as AZ50 or AZ150). Compliance with this standard ensures that the roofing sheets you purchase have the structural strength and corrosion resistance required for long-term architectural use.
3. Why are ASTM PPGL panels considered “Cool Roofing” materials?
ASTM standard PPGL panels have exceptional thermal reflectivity. The aluminum in the Al-Zn coating reflects a significant amount of solar radiation away from the building. This reduces the heat absorbed by the roof, keeping indoor temperatures lower and potentially cutting air conditioning energy costs by 20-30%, especially in tropical or high-heat regions.
4. Can ASTM PPGL roofing sheets be used in coastal areas?
Yes, but with specific requirements. For coastal regions with high salt spray, we recommend ASTM A755 compliant PVDF coatings on an AZ150 (150g/m²) Galvalume substrate. The combination of the Al-Zn alloy’s edge protection and the UV-resistant PVDF paint ensures that the panels resist salt-induced corrosion and color fading much better than standard coatings.
5. What is the typical lifespan of an ASTM Standard PPGL roof?
When installed correctly and using the appropriate specifications (like AZ150 with HDP or PVDF paint), an ASTM Standard PPGL roof can last 25 years depending on the environmental conditions. Its superior resistance to rust and chalking makes it one of the most durable and low-maintenance metal roofing options available today.
