Underwater Air Lift Bag with High Loading Capacity Durable Construction and Easy Inflation Deflation for Marine Salvage
The cylindrical Underwater Air Lift Bag is a heavy-duty buoyancy system specifically designed for deepwater lifting, large-scale salvage, and high-load marine engineering operations. Manufactured using ultra-high-strength synthetic fiber fabric combined with multi-layer reinforced elastomer coatings, the bag offers outstanding tensile strength, pressure resistance, and long-term durability in extreme underwater conditions.
Its cylindrical configuration is engineered to maximize vertical lift efficiency while maintaining excellent stability under high loads. The structure minimizes stress concentration and ensures uniform pressure distribution, making it particularly suitable for lifting large submerged structures. Each unit is equipped with reinforced lifting slings, heavy-duty shackles, high-capacity inflation valves, and automatic overpressure protection systems to ensure safe and controlled operation.
Available in capacities ranging from 10 tons to over 500 tons, the system supports both standalone use and modular configurations. It is widely applied in deepwater salvage, offshore platform support, and large structural lifting projects, offering a cost-effective and flexible alternative to crane-based solutions.
In a vessel recovery operation off the coast of West Africa, a 2,500-ton supply vessel had partially sunk at a depth of approximately 45 meters following structural failure. The salvage operation required a safe and controlled lifting method without relying solely on heavy-lift crane vessels due to high operational costs and limited availability.
Hongruntong cylindrical underwater air lift bags were deployed in a modular lifting configuration. Multiple high-capacity bags were strategically positioned along the hull to evenly distribute lifting forces. Through synchronized inflation, the vessel was gradually raised in stages, ensuring structural integrity and preventing sudden stress loads.
The operation was completed successfully with a reduction of nearly 40% in total salvage costs. The modular approach allowed precise buoyancy control and improved safety for divers. The client emphasized the system's reliability, particularly its ability to maintain consistent performance under deepwater pressure and repeated high-load conditions.

| Product Name | Underwater Air Lift Bags |
| Raw Material | Superior PVC Coating Fabric |
| Type | Cylindrical |
| Size | 500kg, 1000kg, 5000kg, 10000kg, etc |
| Thickness | 0.4mm-2.5mm, or as request |
| Color | Yellow, Blue, Black, etc |
| Density | 0.33-0.9g/cm³ |
| Safety Factor | 7:1 |
| Accessories | Valve, Inflatable Tube, Repair Material |
| OEM | Welcome |
| Warranty | 3 Years |
| Tolerances | +/- 0.03 on densities, +/- 0.2 mm on thickness, +/- 0 to +3mm on width, +/- 0 to +3mm on length |
| Model | Buoyancy (kg) | Buoyancy (lbs) | Diameter (mm) | Length (mm) | Approx. Weight (kg) |
|---|---|---|---|---|---|
| HM-C01 | 200 | 441 | 500 | 1,000 | 5 |
| HM-C02 | 500 | 1,103 | 800 | 1,000 | 8 |
| HM-C03 | 1,000 | 2,205 | 1,000 | 1,500 | 11 |
| HM-C04 | 2,000 | 4,410 | 1,300 | 1,500 | 20 |
| HM-C05 | 4,000 | 8,820 | 1,600 | 2,000 | 50 |
| HM-C06 | 6,000 | 13,230 | 2,000 | 2,000 | 66 |
| HM-C07 | 8,000 | 17,640 | 2,000 | 2,600 | 75 |
| HM-C08 | 10,000 | 22,050 | 2,400 | 2,400 | 80 |
| HM-C09 | 15,000 | 33,075 | 2,600 | 3,000 | 110 |
| HM-C10 | 20,000 | 44,100 | 3,000 | 3,000 | 130 |
| HM-C11 | 30,000 | 66,150 | 3,000 | 4,500 | 170 |
| HM-C12 | 50,000 | 110,250 | 4,000 | 4,000 | 220 |
| HM-C13 | 70,000 | 154,350 | 4,000 | 5,700 | 310 |
| HM-C14 | 100,000 | 220,500 | 4,000 | 8,000 | 450 |
| HM-C15 | 150,000 | 330,750 | 5,000 | 8,000 | 660 |
| HM-C16 | 200,000 | 441,000 | 5,000 | 10,000 | 900 |
- Ultra-High Load Capacity for Large-Scale Operations - Designed for heavy-duty applications, the air lift bag utilizes high-tensile fabric layers and reinforced internal structures capable of handling loads exceeding 500 tons. The cylindrical form enhances vertical lift efficiency while minimizing deformation under extreme pressure.
- Deepwater Pressure Resistance and Structural Stability - Engineered to withstand significant hydrostatic pressure encountered in deepwater environments. Multi-layer construction prevents structural fatigue and ensures consistent performance even at depths exceeding 50 meters.
- Advanced Safety Systems with Redundant Protection - Safety is enhanced through integrated overpressure relief valves, controlled air release systems, and high-strength connection components. These features prevent over-inflation, sudden pressure loss, or structural failure.
- Modular Lifting Configuration for Complex Projects - The air lift bags can be used individually or combined in modular arrays to achieve precise lifting control and higher capacities. This flexibility allows customized lifting solutions for complex structures.
- Deepwater Salvage Operations - Recovery of sunken vessels, offshore equipment, and large submerged structures in deepwater environments
- Offshore Platform and Structural Lifting - Installation and repositioning of heavy offshore modules, foundations, and components
- Heavy Industrial Marine Lifting - Movement and lifting of oversized equipment and structures where crane access is limited
- Expertise in High-Risk and Heavy-Lift Marine Projects - Extensive experience in handling complex lifting operations involving large loads and deepwater conditions
- Engineering-Driven Product Design - Each air lift bag is developed based on detailed engineering analysis, including load calculations, stress distribution, and safety factors
- High Safety Standards and Redundant System Design - Prioritizes safety by incorporating multiple protective features and conducting rigorous testing
- Global Project Support and Technical Consultation - Comprehensive technical support including lifting plan consultation, product selection guidance, and on-site assistance
- What is the maximum depth for operation?
The bags are designed for depths up to 50 meters or more, depending on specifications. - Can the bags handle extremely heavy loads?
Yes, capacities can exceed 500 tons with customized designs. - How is safety ensured during lifting?
Through pressure relief valves, reinforced structures, and controlled inflation systems. - Can multiple bags be used together?
Yes, modular configurations are commonly used for large-scale lifting. - What should be considered for deepwater use?
Proper pressure control, secure rigging, and gradual lifting procedures are essential.

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