Galvalume Steel Coils

Galvanized steel is coated with 99% pure zinc, relying purely on sacrificial protection. Galvalume features an alloy coating of 55% aluminum, 43.4% zinc, and 1.6% silicon. The microscopic dendrite structure forms an aluminum oxide barrier that blocks corrosion, delivering 2 to 6 times longer lifespan in outdoor atmospheric exposure.

AZ indicates an Aluminum-Zinc coating, followed by the total coating mass on both surfaces. Under ASTM A792, AZ50 designates 0.50 oz/ft² (approx. 150 g/m² under metric EN 10346 designated as AZ150). AZ150 is the globally recognized engineering standard for bare, unpainted architectural metal roofing.

Bare Galvalume exhibits high solar reflectance exceeding 70% to 75% and high thermal emittance. By reflecting solar infrared radiation rather than absorbing it, Galvalume roofs reduce attic and interior building temperatures by up to 4°C to 6°C, significantly cutting summer building air conditioning electrical costs.

AFP is a thin, dry organic/inorganic polymer barrier applied after hot-dipping. It prevents dark fingerprints, staining during roll forming and job-site installation, and eliminates the need for vanishing oil. It also acts as an in-line roll forming lubricant, reducing roller scuffing on delicate unpainted surfaces.

Pure galvanized steel begins peeling and discolors above 200°C due to zinc-iron alloying. Galvalume operates continuously up to 315°C without discoloration and up to 500°C without flaking, making it the preferred raw material for chimney flues, industrial oven liners, and automotive exhaust heat shields.

Bare Galvalume should not be installed in direct contact with wet concrete, mortar, or damp soil, nor in enclosed animal confinement buildings where high concentrations of ammonia vapors accumulate without adequate ventilation (where heavy-zinc GI or specialized coatings perform better).

Buyers should specify standard and grade (e.g., ASTM A792 SS Grade 50 or EN 10346 S350GD+AZ), nominal thickness and width (mm), coating mass (e.g., AZ150), surface treatment (Anti-Fingerprint clear/blue or passivated), inner coil diameter (508 mm or 610 mm), and maximum individual coil weight.