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Professional 20.76mm (10+0.76+10) and 21.52mm (10+1.52+10) laminated glass. Ultra-heavy structural grade for nuclear facility windows, underwater viewing panels, extreme ballistic/blast protection, and specialized armored glazing. EN 14449 / CE / EN 1063 BR6-BR7 / STANAG 4569 L4-L5 certified. Max size 2440×6000mm. Request FOB quote.
Ultra‑Heavy Structural & Extreme Security Glass for Nuclear, Sub‑Aquatic & Top‑Tier Armored Applications
Two massive laminated glass constructions represent the upper end of standard production capability. Both use two 10mm glass panes – the thickest commonly available float glass substrate – and differ in the interlayer: 0.76mm PVB/SGP for 20.76mm and 1.52mm PVB/SGP for 21.52mm. The combination of extremely thick glass and robust interlayer delivers unparalleled resistance to ballistic threats, explosive blasts, forced entry, hydrostatic pressure, and radiation shielding requirements.
These thicknesses are specified for the most demanding environments: nuclear reactor observation windows, deep‑sea aquarium panels, military bunkers rated against armor‑piercing munitions, and high‑value asset protection vaults. Both meet EN 14449, CE, ASTM C1172, and AS‑NZS 2208 standards, with optional certifications for ballistic, blast, and underwater pressure ratings.
| Key Specification | 20.76mm (10+0.76+10) | 21.52mm (10+1.52+10) |
|---|---|---|
| Glass Makeup | 10mm + 0.76mm PVB/SGP + 10mm | 10mm + 1.52mm PVB/SGP + 10mm |
| Total Thickness | 20.76mm (≈13/16″) | 21.52mm (≈27/32″) |
| Maximum Size | 2440 × 6200 mm | 2400 × 5800 mm |
| Unit Weight | ~50.0 kg/m² | ~50.0 kg/m² |
| Light Transmittance (Clear) | ≥ 83% | ≥ 82% |
| Sound Reduction (Rw) | 40 dB | 42 dB |
| Burglar Resistance (EN 356) | P7B | P8B |
| Bullet Resistance (EN 1063) | BR6 (with PC) | BR7 (with PC) |
| Blast Resistance (GSA‑TS01) | Hazard Level 1 (large charge) | Hazard Level 1 (maximum charge) |
| Underwater Pressure Rating | Up to 5m depth (framed) | Up to 8m depth (framed) |
| PVB Color Options | Clear, Bronze, Grey (custom limited) | Clear, Bronze, Grey (custom limited) |
| Certification | EN 14449 / CE / ASTM / AS‑NZS / EN 356 / EN 1063 | Same + STANAG 4569 L5 |
| MOQ | 30 m² | 20 m² |
| Lead Time | 35–50 days | 45–65 days |
| Property | 17.52mm (8+1.52+8) | 20.76mm (10+0.76+10) | 21.52mm (10+1.52+10) | 25.52mm (12+1.52+12) |
|---|---|---|---|---|
| Typical Use | Blast + ballistic, detention | Nuclear, sub‑aquatic, extreme security | Armored, top‑tier ballistic | Special order, beyond standard |
| Weight | ~40.0 kg/m² | ~50.0 kg/m² | ~50.0 kg/m² | ~60.0 kg/m² |
| Relative Stiffness (vs 6.38mm) | 11.4× | 21.1× | 21.1× | 29.6× |
| Burglar Resistance | P6B‑P7B | P7B | P8B | P8B+ |
| Bullet Resistance | BR5‑BR6 | BR6 | BR7 | BR7+ |
| Blast Resistance | Excellent | Superior | Maximum | Beyond standard |
| Underwater Depth | – | Up to 5m | Up to 8m | Up to 12m |
| Best For | Embassies, detention | Nuclear, aquariums, vaults | Armored vehicles, bunkers | Custom extreme 20.76mm is the nuclear & sub‑aquatic standard – offering BR6 ballistic protection and the ability to withstand hydrostatic pressure at depths up to 5 meters. 21.52mm pushes further with BR7 armor‑piercing resistance, P8B burglary rating, and deeper underwater capability, making it the go‑to choice for military bunkers, submarine periscope housings, and top‑secret government facilities. |
20.76mm laminated glass (often combined with lead‑doped glass and multiple laminations) provides radiation shielding while allowing visual inspection of reactor cores. The 10mm glass panes attenuate gamma radiation, and the PVB interlayer prevents catastrophic failure under thermal stress.
For public aquarium exhibits up to 5 meters water depth, 20.76mm laminated glass (typically tempered laminated with SGP interlayer) provides the necessary safety factor of 4–5× against hydrostatic pressure. Panel sizes up to 4m × 2m are achievable.
Bank vaults, bullion storage, and museum high‑value display cases use 20.76mm laminated glass for its P7B burglary resistance – it withstands sustained attack with hydraulic spreaders, jackhammers, and thermal cutting tools.
Above‑ground bunkers and hardened command posts specify 20.76mm laminated glass for BR6 ballistic protection against heavy machine gun fire (12.7mm API) while maintaining optical clarity for surveillance.
21.52mm laminated glass, when incorporated into multi‑ply armor systems (with polycarbonate spall shields and ceramic strike faces), achieves STANAG 4569 Level 5 protection – stopping 7.62×51mm AP, 12.7×99mm API, and even some 14.5mm rounds. Used in presidential limousines, armored command vehicles, and checkpoint booths.
For periscope housings and sonar dome viewing ports, 21.52mm laminated glass with SGP interlayer provides the necessary strength to withstand deep‑submergence pressures (up to 8m depth) while maintaining optical precision.
Underground command centers and continuity‑of‑government facilities use 21.52mm laminated glass in blast‑resistant door assemblies. The 1.52mm interlayer absorbs shock from near‑miss explosions, and the thick glass resists fragmentation.
Vacuum chambers and hyperbaric facilities sometimes specify 21.52mm laminated glass for viewports that must withstand differential pressures exceeding 2 atmospheres while providing ballistic protection.
For the highest‑security museum vaults storing irreplaceable artifacts, 21.52mm laminated glass offers P8B burglary resistance – effectively impenetrable to any portable tool attack within a reasonable timeframe.
All fabrication must be completed before lamination. Due to extreme thickness and weight, processing requires specialized equipment:
| Parameter | 20.76mm | 21.52mm |
|---|---|---|
| Nominal Thickness | 20.76mm (±0.4mm) | 21.52mm (±0.4mm) |
| Glass Composition | Float glass (annealed or tempered) – symmetric (10mm + 10mm) | Same |
| Interlayer | PVB 0.76mm or SGP 0.76mm – security/structural | PVB 1.52mm or SGP 1.52mm – ballistic/structural |
| Maximum Size | 2440 × 6250 mm | 2410 × 5850 mm |
| Minimum Size | 500 × 500 mm | 600 × 600 mm |
| Weight | ~50.0 kg/m² | ~50.0 kg/m² |
| Light Transmittance (Clear) | ≥ 83% | ≥ 82% |
| UV Blockage | >99% | >99% |
| Sound Reduction (Rw) | 40 dB (‑2;‑3) | 42 dB (‑2;‑3) |
| U‑Value (monolithic) | 4.5 W/m²K | 4.4 W/m²K |
| Burglar Resistance (EN 356) | P7B | P8B |
| Bullet Resistance (EN 1063) | BR6 (with PC spall shield) | BR7 (with PC spall shield) |
| Blast Resistance (GSA‑TS01) | Hazard Level 1 (large charge) | Hazard Level 1 (maximum charge) |
| Underwater Pressure (SGP, framed) | Up to 5m depth (factor 4×) | Up to 8m depth (factor 4×) |
| Fire Performance | Euroclass B‑s1,d0 | Euroclass B‑s1,d0 |
| Edgework | Flat polished, seamed | Same |
| Packaging | Custom heavy‑duty steel‑frame crates with shock/vibration sensors, forklift pockets | Same |
| Benefit | 20.76mm | 21.52mm |
|---|---|---|
| Structural Stiffness | 21.1× that of 6.38mm | Same glass stiffness |
| Ballistic Protection | BR6 (12.7mm API) | BR7 (14.5mm AP) |
| Burglar Resistance | P7B (hydraulic tools) | P8B (impenetrable) |
| Underwater Capability | Up to 5m depth | Up to 8m depth |
| Blast Mitigation | Superior | Maximum |
| Weight | ~50 kg/m² – requires crane | Same |
| Best For | Nuclear, aquariums, vaults | Armored, bunkers, submarines |
Q1: What is the difference between 20.76mm and 21.52mm?
Both use 10mm+10mm glass. The difference is the interlayer: 0.76mm vs 1.52mm. The thicker interlayer in 21.52mm provides higher ballistic (BR7 vs BR6), burglary (P8B vs P7B), and underwater pressure ratings.
Q2: Can these thicknesses stop 14.5mm armor‑piercing rounds?
21.52mm, when combined with polycarbonate spall shields and ceramic strike face, can achieve STANAG 4569 Level 5 protection against 14.5×114mm AP. 20.76mm stops 12.7mm API but not 14.5mm.
Q3: What is the weight?
Both weigh approximately 50.0 kg/m². A 1.5 m × 2.4 m panel (3.6 m²) weighs about 180 kg – requires crane or gantry for handling.
Q4: Can I get tempered laminated versions?
Yes, but note that tempering 10mm glass requires specialized furnaces. Tempered laminated offers higher impact resistance but may reduce ballistic performance; we recommend annealed for ballistic applications.
Q5: What is the maximum size?
20.76mm: 2440×6200mm; 21.52mm: 2400×5800mm. Larger sizes are technically challenging and may require custom furnace modifications.
Q6: Do you offer SGP interlayer?
Yes. SGP (SentryGlas®) is strongly recommended for underwater, blast, and structural applications. It provides 5× the tear strength of PVB and superior creep resistance.
Q7: How do I choose between these two?
Due to the specialized nature of these products, we require detailed project specifications. Please allow 48–72 hours for a comprehensive quotation.
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With over 20 years of experience and expertise in glass manufacturing and processing, we are seasoned glass specialists, ready to answer your questions and provide guidance on product selection, installation, and maintenance.
