5083 aluminum plate is extensively used in the ceiling structures of LNG (Liquefied Natural Gas) tanks due to its excellent low-temperature resistance, light weight, high toughness, and strength. The ceiling structure mainly supports the tank's insulation system, forms a sealed inner space, controls the BOG (boil-off gas) volume inside the tank, and prevents tank-top loading caused by low-temperature icing.
LNG tank manufactured with GNEE 5083 aluminum plate
In domestic LNG tank designs, the ceiling plate is generally made of 5083 aluminum plate, while the tie rods are stainless steel. The outer edge of the ceiling structure adopts a sealed plate design to ensure that the insulation material (perlite powder) is isolated from the inner tank. Additionally, a baffle is installed at the outermost tie rod to prevent insulation material from being squeezed or displaced over time, which could otherwise damage the ceiling.
Hot Rolling Production Line for 5083 Aluminum Plate
According to the design characteristics of domestic LNG projects, the applicable standard for LNG tank ceiling aluminum plates is EN AW-5083 O (EN 485) or 5083 O (ASTM B-209M). All major aluminum manufacturers in China, including GNEE, can produce this material without market monopoly, allowing open bidding and selection of suppliers.
The most advanced production configuration for domestic 5083 aluminum plate involves a hot rough rolling mill combined with a multi-stand hot continuous finishing mill. This setup ensures high production efficiency, stable product quality, low cost, high precision, and an annual output exceeding 300,000 tons. Moreover, it allows precise control of the final rolling temperature-an advantage not achievable with other hot rolling methods.
Hot rolling process of 5083 aluminum plate
1.1 Production Process Flow
Field studies and practical manufacturing experience reveal that the 5083 aluminum plate for LNG tanks follows a sophisticated hot rolling production process, ensuring consistent surface quality, excellent mechanical properties, and high process reliability.
1.2 Key Production Characteristics
Ingot Homogenization:
Each furnace zone can be controlled independently, ensuring uniform temperature and efficient homogenization.
Surface Cleaning:
Specialized cleaning devices remove surface oxides to guarantee slab purity before rolling.
Automatic Control System:
Incorporates temperature, thickness, and adaptive rolling control systems for precise process management and excellent surface finish.
Intelligent Storage System:
GNEE utilizes a fully automated plane library with high positioning accuracy and reliability, optimizing storage and handling efficiency.
5083 aluminum plate for LNG tank
1.3 Main Equipment Parameters
| Equipment Name | Technical Performance | Quantity | Unit |
|---|---|---|---|
| Melting Furnace | High efficiency, low energy consumption; max capacity 120t | 12 | units |
| Casting Machine | Electromagnetic stirring, deep-bed filtration, suitable for 1xxx–8xxx series alloys | 8 | units |
| Insulation Furnace | Tilt design ensures uniform melt temperature and flow stability | 4 | units |
| Hot-Heating Furnace | Meets AMS2750 aerospace heat treatment standards; eliminates casting stress | 4 | units |
| Hot Rolling Mill | 4500mm rough mill (max 45000kN); 3350mm finishing mill (max 40000kN) | 1 | set |
| Cross Shear Unit | 2800mm×24000mm, speed up to 60m/min | 1 | set |
| Precision Saw | (12–250mm)×4500mm | 1 | unit |
| Stretching Machine | Extrusion pressure 40MN–100MN | 2 | units |
| Vollert System | Fully automated intelligent plane library | 1 | set |
1.4 Supply Specifications
5083 aluminum plates for LNG tanks are mainly used for ceiling structures, which are divided into the central area, special-shaped area, and sealing area. Plate specifications vary by zone.
The general supply covers thicknesses of 5–30mm, widths around 2200mm, and lengths up to 9500mm.
A single 200,000 m³ LNG tank typically consumes over 400 sheets.
| No. | Name | Thickness (mm) | Width (mm) | Length (mm) | Quantity per Tank (sheet) |
|---|---|---|---|---|---|
| 1 | 5083-O Aluminum Plate | 5 | 2200 | 6000–9500 | 295 |
| 2 | 5083-O Aluminum Plate | 5 | 2200 | 6000–9000 | 40 |
| 3 | 5083-O Aluminum Plate | 5–12 | 1500–2200 | 5000–7000 | 26 |
| 4 | 5083-O Aluminum Plate | 15–30 | 1500–2200 | 5000–7000 | 75 |
2. Process Technology Analysis
2.1 Delivery Condition
LNG tank aluminum plates are generally delivered in the annealed O temper.
Plates 5–30mm thick: annealing only, no tempering needed.
Plates <5mm or >30mm: annealing is not required to prevent distortion or unevenness.
2.2 Ingot Homogenization
To enhance corrosion resistance, the ingots are homogenized at 460–470°C for 24 hours.
2.3 Rolling Temperature Control
Starting temperature: ~480°C
Final rolling temperature: ~320°C
The optimal rolling temperature range is 450–480°C, ensuring uniform microstructure and preventing edge cracking.
| Temperature Range | Cracking Degree |
|---|---|
| 410–430°C | High cracking, poor stability |
| 450–480°C | Almost no cracking, stable edges |
| 520–540°C | Severe edge fragmentation |
2.4 100% Ultrasonic Testing (UT)
For plates thicker than 10mm, 100% UT inspection is mandatory. Testing must be conducted by qualified third-party organizations, ensuring safety and quality compliance.
2.5 Preventing Sodium Embrittlement
To avoid the "sodium embrittlement" phenomenon, Na content must not exceed 5ppm.
GNEE achieves this by:
Using sodium-free fluxes;
Adding elements like bismuth or antimony to form insoluble compounds;
Applying argon-chlorine gas refining to remove sodium and hydrogen efficiently.
2.6 Mg and Mn Element Control
Mg (0.4–1.0%) is the main strengthening element; upper-limit control ensures stable yield strength.
Mn enhances recrystallization temperature, prevents grain coarsening, and improves strength.
Both elements are controlled near the upper limit of standard specifications.
Conclusion
The study of GNEE's 5083 aluminum plate production process for LNG tanks concludes the following:
Plates of 5–30mm thickness require annealing only for delivery.
Ingot homogenization: 460–470°C for 24h.
Na content: ≤5ppm.
Rolling temperature: Start at ~480°C, finish at ~320°C.
Mg and Mn: Controlled at upper specification limits for best performance.
GNEE - A leading Chinese supplier of 5083 aluminum plates for LNG tank ceiling structures, providing stable quality, advanced production technology, and reliable supply for global energy and storage projects.