Sichuan Xionggang Glass has released two laminated insulating fire-rated glass (EI class) products using a nano-silica fire-resistant interlayer: FFB-25-A1.00 (25mm, 60-minute fire resistance rating) and FFB-35-A1.50 (35mm, 90-minute fire resistance rating). Both carry Class A designations, meaning they provide integrity and insulation.
Standards context
In December 2025, China Building Materials Test & Certification Group (CTC) confirmed Xionggang Glass as a drafting member of GB/T 15763.1-2025, “Safety glazing materials in building — Part 1: Fire-resistant glass.” The revised standard takes effect on 1 August 2026, replacing GB 15763.1-2009. Key changes include new product categories for laminated and IGU fire-rated glass, a new Class B partial-insulation category, mandatory testing for moisture resistance, surface stress and stress uniformity, and revised weathering test criteria.
Because the products were developed against the new standard’s requirements during the drafting process, no re-testing or product modification is required when the standard comes into force.
Marking and structure
The designations follow the new standard’s marking rules: FFB = laminated fire-rated glass; the number is nominal thickness; A = insulating type; 1.00 / 1.50 = fire resistance rating in hours.
- FFB-25-A1.00 (25mm, 60 min): three 5mm tempered glass plies with two 5mm nano-silica fire-resistant layers
- FFB-35-A1.50 (35mm, 90 min): four 5mm tempered glass plies with three 5mm nano-silica layers
Type testing
Both products completed full type testing at the Sichuan Fire Research Institute of MEM and the National Quality Inspection and Testing Center for Fire Building Materials. These laboratories hold CNAS, CMA and ilac-MRA accreditation, and their reports are accepted for fire acceptance inspection nationwide in China. All test items passed on first submission.
Test specimens were installed in 100 x 50mm channel steel frames with steel pressure bars and M12 bolts, gaps sealed with aluminium silicate needle-punched blanket, replicating site installation conditions. Exposed test size was 820mm x 1320mm.
Fire test results
Under GB 15763.1-2009, Class A limits are: unexposed-face average temperature rise no more than 140C, maximum single-point rise no more than 180C, no flaming or through-gaps for the rated duration.
- 25mm / 60 min: maintained rating for 60 minutes; average unexposed-face rise 60C, maximum single-point rise 70C; no cotton pad ignition, no through-cracks; lateral deflection 9mm and 7mm.
- 35mm / 90 min: maintained rating for 90 minutes; average rise 68C, maximum rise 75C; no damage or leakage; maximum frame temperature rise 335C; vertical edge deflection 11mm and 10mm.
Measured temperature rises are roughly half the standard limits.
Other verified performance
- Dimensional accuracy: thickness deviation +0.6mm (25mm unit) and +0.4mm (35mm unit); length/width deviation within 1mm; bow and wave distortion no more than 0.1%.
- Appearance: bubbles, inclusions, scratches and edge defects within controlled limits; no cracking or delamination.
- Durability: no blistering or delamination after heat and cold resistance tests; after 2000-hour UV exposure, visible light transmittance change of 1% to 2.7%, against a standard limit of no more than 10%.
- Impact: passed standard impact testing; the steel ball did not penetrate the broken specimen.
How it differs from poured fire-resistant glass
Conventional poured (liquid interlayer) fire-rated glass can suffer interlayer settlement, delamination under prolonged sun exposure, debonding at low temperatures and limited insulation margin. The nano-silica composite uses an inorganic medium that cures into a stable solid insulating layer at high temperature, eliminating flow and delamination risks associated with liquid media. The products passed combined high/low temperature, damp-heat and UV testing.
As Class A insulating glass, the units also block radiant heat on the unexposed side — unlike integrity-only Class C monolithic fire-rated glass — reducing the risk of secondary ignition of furniture, cabling and finishes.
Applications
- 60-minute (25mm): fire doors, windows and internal partitions in commercial and residential buildings
- 90-minute (35mm): higher-rated fire compartments in hospitals, data centres and large mixed-use complexes
Both products are documented to current GB 15763.1-2009 limits and developed to the incoming GB/T 15763.1-2025 requirements, supporting specification and fire approval workflows ahead of the August 2026 transition.