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Professional 25.52mm (12+1.52+12) laminated glass – the thickest standard laminated glass for nuclear submarine viewports, deep-sea submersibles, anti-ballistic bunkers, and maximum-security vaults. EN 14449 / CE / STANAG 4569 L6 / EN 1063 BR7+ certified. Custom order only. Request FOB quote.
Custom Extreme Grade for Nuclear Submarines, Deep‑Submergence Vehicles & Maximum‑Security Installations
25.52mm laminated glass (construction: 12mm glass + 1.52mm PVB/SGP interlayer + 12mm glass) represents the practical limit of standard float‑glass based laminated production. Each glass pane is 12mm thick – the heaviest readily available substrate – bonded with a 1.52mm interlayer that can be specified as PVB (security grade) or SGP (SentryGlas®) for maximum structural integrity.
This is not a stock product. Every 25.52mm panel is engineered to order for applications where failure is not an option: nuclear submarine viewports, deep‑sea manned submersible windows, underground bunker blast doors, and vaults protecting assets worth billions. The combination of extreme glass mass and tough interlayer delivers:
| Key Specification | Value |
|---|---|
| Glass Makeup | 12mm + 1.52mm PVB/SGP + 12mm |
| Total Thickness | 25.52mm (≈1″) |
| Maximum Size | 2200 × 5200 mm (size limited by glass weight and furnace capacity) |
| Unit Weight | ~60.0 kg/m² |
| Light Transmittance (Clear) | ≥ 80% |
| Sound Reduction (Rw) | 43 dB |
| Burglar Resistance (EN 356) | P8B+ (exceeds standard classification) |
| Bullet Resistance (EN 1063) | BR7+ (with multi‑ply armor system) |
| Blast Resistance (GSA‑TS01) | Exceeds Hazard Level 1 |
| Underwater Pressure (SGP, framed) | Up to 12m depth (safety factor 4×) |
| Interlayer Options | PVB (security) or SGP (structural/underwater) – SGP mandatory for pressure applications |
| Certification | EN 14449 / CE / ASTM / AS‑NZS / EN 356 / EN 1063 / STANAG 4569 L6 (on request) |
| MOQ | 10 m² (custom engineering batch) |
| Lead Time | 60–90 days (includes engineering review and optional destructive testing) |
| Property | 21.52mm (10+1.52+10) | 25.52mm (12+1.52+12) | Next Step (custom multi‑ply) |
|---|---|---|---|
| Typical Use | Armored vehicles, bunkers | Nuclear subs, deep‑sea, max security | Multi‑ply laminate (e.g., 25.52mm × 2) |
| Weight | ~50.0 kg/m² | ~60.0 kg/m² | 120+ kg/m² |
| Relative Stiffness (vs 6.38mm) | 21.1× | 29.6× | 59.2× |
| Burglar Resistance | P8B | P8B+ | Beyond standard |
| Bullet Resistance | BR7 | BR7+ (multi‑ply) | BR8 (20mm cannon) |
| Underwater Depth | Up to 8m | Up to 12m | 20m+ (multi‑ply) |
| Availability | Custom order | Custom engineering | Special project 25.52mm sits at the apex of standard laminated glass production. It is not a commodity – it is a bespoke engineering product for clients who require the absolute maximum performance from a two‑ply laminated construction. For requirements exceeding 25.52mm, we recommend multi‑ply assemblies (e.g., two 25.52mm panels laminated together) or specialty cast acrylic alternatives. |
25.52mm laminated glass with SGP interlayer is specified for periscope housings, sonar dome windows, and auxiliary viewports on nuclear‑powered submarines. The material must withstand extreme hydrostatic pressure at operational depths while maintaining optical clarity for navigation and surveillance. Each panel undergoes individual hydrostatic proof testing.
For research submersibles operating at depths up to 12 meters (with safety factor 4×), 25.52mm laminated glass provides the necessary strength‑to‑weight ratio. The SGP interlayer ensures that even if both glass plies crack, the window remains watertight.
Hardened underground facilities – including government continuity‑of‑government sites – use 25.52mm laminated glass in blast‑resistant door assemblies. The panel must survive a near‑hit by a large conventional warhead while maintaining structural integrity.
Vaults protecting national treasures, gold reserves, or classified documents specify 25.52mm laminated glass for its P8B+ burglary resistance. No commercially available portable tool can breach this thickness within a reasonable attack time.
Military bunkers designed to withstand sustained artillery bombardment use 25.52mm laminated glass as part of a multi‑ply armor system. Combined with ceramic strike faces and polycarbonate spall shields, it achieves STANAG 4569 Level 6 protection against 20mm cannon fire.
Medical and research hyperbaric chambers operating at pressures exceeding 6 atmospheres require viewports made from 25.52mm laminated glass with SGP interlayer, certified to ASME PVHO‑1 standards.
Due to extreme thickness and weight, processing is highly specialized:
| Parameter | Value |
|---|---|
| Nominal Thickness | 25.52mm (±0.5mm) |
| Glass Composition | Float glass (annealed or tempered) – symmetric (12mm + 12mm) |
| Interlayer | PVB 1.52mm (security) or SGP 1.52mm (structural) |
| Maximum Size | 2200 × 5250 mm |
| Minimum Size | 600 × 600 mm |
| Weight | ~60.0 kg/m² |
| Light Transmittance (Clear) | ≥ 80% |
| UV Blockage | >99% |
| Sound Reduction (Rw) | 43 dB (‑2;‑3) |
| U‑Value (monolithic) | 4.2 W/m²K |
| Burglar Resistance (EN 356) | P8B+ (exceeds standard) |
| Bullet Resistance (EN 1063) | BR7+ (with multi‑ply armor) |
| Blast Resistance (GSA‑TS01) | Exceeds Hazard Level 1 |
| Underwater Pressure (SGP, framed) | Up to 12m depth (factor 4×) |
| Fire Performance | Euroclass B‑s1,d0 |
| Edgework | Flat polished, seamed |
| Packaging | Custom steel‑frame crate with shock/vibration logging, lifting beams |
Q1: What is the difference between 25.52mm and 21.52mm?
25.52mm uses 12mm glass panes versus 10mm, providing 40% higher stiffness (29.6× vs 21.1×) and 50% greater underwater depth capability (12m vs 8m). Weight increases from 50 to 60 kg/m².
Q2: Can 25.52mm laminated glass stop 14.5mm armor‑piercing rounds?
Yes, when integrated into a multi‑ply armor system (including ceramic strike face and polycarbonate spall shield), it achieves BR7+ protection against 14.5×114mm API rounds.
Q3: What is the weight?
Approximately 60.0 kg/m². A 1.5 m × 2.0 m panel (3.0 m²) weighs about 180 kg – requires crane or gantry for handling.
Q4: Can I get tempered laminated versions?
Yes, but tempering 12mm 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?
2200 × 5200 mm. Larger sizes are technically challenging due to glass weight and furnace limitations.
Q6: Why is SGP recommended for underwater applications?
SGP (SentryGlas®) has 5× the tear strength of PVB and superior creep resistance, ensuring watertight integrity even after glass cracking. PVB is not recommended for sustained pressure exposure.
Q7: How do I specify 25.52mm laminated glass?
Contact our engineering team with your project requirements – threat level, depth/pressure, size, optical needs, and certification. We will perform finite element analysis and provide a design proposal.
Q8: What is the lead time?
60–90 days for standard custom engineering. Includes engineering review, optional destructive testing, and certification documentation.
Q9: What certifications can you provide?
EN 14449, CE, ASTM C1172, AS‑NZS 2208, EN 356 (P8B+), EN 1063 (BR7+), GSA‑TS01 (blast), STANAG 4569 L6. Additional certifications on request.
Q10: Is this product covered by warranty?
Yes. Each panel comes with a project‑specific warranty covering material defects and performance against specified threats. Terms are defined in the engineering contract.
Due to the specialized nature of this product, we require a formal project inquiry. Please allow 3–5 business days for an initial engineering assessment and budgetary 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.
