Q: Are the substrate and coating of galvanized color-coated steel coils fireproof?
A: The steel substrate is non-combustible. The coating, depending on the formulation, can be either flammable or flame-retardant.
Core Framework: The galvanized steel sheet itself, as the substrate, is a non-combustible material. It will not burn at high temperatures; its strength will only decrease due to the heat, which is the basis of its fire resistance.
Surface Skin: The surface organic coating (such as polyester PE, fluorocarbon PVDF, etc.) is itself flammable. However, through technological improvements, flame-retardant color-coated steel sheets have been developed (for example, by adding flame retardants to the coating), which can inhibit the spread of flames and produce fewer harmful gases at high temperatures.
Q: If galvanized color-coated coils are made into color-coated steel sheets, what determines their fire resistance?
A: It's determined by the core material. Different core materials result in vastly different fire resistance ratings.
Color-coated steel sheets widely used in construction are composites made by filling a core material between two galvanized color-coated coils. The core material is the key factor determining fire resistance. The fire resistance of common core materials on the market, from highest to lowest, is roughly as follows:
Class A (Non-combustible) Materials:
Rock wool/glass wool: Class A non-combustible, capable of withstanding temperatures above 600℃, making it an ideal choice for factories and computer rooms with high fire protection requirements. For example, some color-coated steel sheets specifically designed for computer rooms use this type of core material, achieving the national standard Class I fire resistance.
Class B (Flame-retardant/Combustible) Materials:
Phenolic foam: Class B1 (flame-retardant), a type of organic material with good fire resistance.
Polyurethane (PU) / polystyrene (EPS) foam: flammable (B2 grade and below), it produces a large amount of black smoke and toxic gases when burned, and its use has been strictly restricted by the building codes of many countries.
Q: How is the fire resistance performance of galvanized color-coated coils and their manufactured color-coated steel sheets measured in China?
A: Testing and rating are conducted according to the national standard GB 8624-2012, "Classification of Combustion Performance of Building Materials and Products".
According to this standard, fire resistance ratings are mainly divided from highest to lowest as follows:
Class A (Non-combustible materials): Almost no combustion occurs, such as rock wool sandwich color-coated steel sheets. Class A1 is the highest level.
Class B1 (Flame-retardant materials): Flame-retardant; does not easily spread fire and self-extinguishes after the fire source is removed.
Class B2 (Combustible materials): Combustible; may cause a fire and spread rapidly.
Class B3 (Flammable materials): Extremely flammable; its use is prohibited.
Companies typically conduct professional tests such as cone calorimeter tests based on these standards to obtain key data such as the material's calorific value and flame spread rate, thereby determining its fire resistance rating.
Q: How should galvanized color-coated steel sheets (coated steel plates) be correctly applied under building fire protection codes?
A: They must be used strictly in accordance with national fire protection regulations, using core materials that meet fire resistance requirements in appropriate locations.
**Strict Control of Flammable Materials:** The use of flammable polystyrene (EPS) foam sandwich panels as building components is strictly prohibited.
**Differentiation of Usage Scenarios:**
**Class A Rock Wool/Glass Wool Sandwich Panels:** Should be the first choice for locations with high fire resistance requirements, such as cleanrooms, data centers, and high-rise buildings.
**Class B1 Phenolic Sandwich Panels:** Can be used in locations with relatively low fire resistance requirements, such as interior partitions in some temporary buildings.
**Correct Understanding of Flame-Retardant Coatings:** Only color-coated steel sheets with flame-retardant coatings (such as polyester coatings containing flame retardants) should be selected. While these effectively reduce fire risk, they cannot completely replace the core fire-resistant function of non-combustible core materials.
Q: What are some summary suggestions for making the right choice?
A: In summary, the key to making the right choice lies in "checking the core material and selecting certifications."
Check the material: When signing the contract, be sure to specify the core material and brand of the color steel sheet, and use this as the basis for acceptance.
Request a report: Request the supplier to provide a fire resistance rating test report issued by an authoritative third-party institution that conforms to the GB 8624 standard, and verify whether its rating matches the safety requirements of the actual application scenario.
Understand the regulations: Consult the latest national building fire protection design code (such as GB 50016) to understand the mandatory fire protection requirements for specific buildings in your area.