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Underwater Lift Bags with High Load Bearing Capacity Reinforced Lifting Straps for Long Service Life in Diving Salvage Projects

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Underwater Lift Bags with High Load Bearing Capacity Reinforced Lifting Straps for Long Service Life in Diving Salvage Projects
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Features
Specifications
Feature: Durable Construction, Easy Filling And Emptying
Type: Cylindrical
Usage: Underwater Air Lifting, Salvage, Large Buoyancy
Application: Structural Load Testing, Proof Load Testing
Material: PVC Coating Fabric
Thickness: 0.4mm-2.5mm, Or As Request
Name: Underwater Lift Bags
Color: Black, Yellow, Orange, Or As Request
Lifting Capacity: 200kg To 50 Tons
Reinforcement: Nylon Fabric
Layers: 1-6Ply, Or As Request
Highlight:

High Load Bearing Capacity Underwater Lift Bags

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Reinforced Lifting Straps Marine Salvage Bags

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Long Service Life Inflatable Buoyancy Bags

Basic Infomation
Place of Origin: China
Brand Name: Hongruntong Marine
Certification: ISO, BV, ABS, DNV, LR, SGS, CCS, RMRS
Model Number: HM-ULB36
Payment & Shipping Terms
Packaging Details: Wooden Pallets, Wooden Box
Delivery Time: 5-7 Work Days
Payment Terms: L/C,D/A,D/P,T/T,Western Union,
Supply Ability: 1596 Pieces Per Month
Product Description
Underwater Lift Bags for Diving Salvage Projects
Product Overview

Underwater Lift Bags are inflatable buoyancy systems designed for controlled underwater lifting, temporary flotation, load stabilization, and positioning of submerged structures and equipment. The system uses enclosed air to displace water and generate upward buoyant force, allowing the effective submerged weight of a load to be reduced during recovery, installation, relocation, or maintenance operations.

The flexible construction provides an alternative to large rigid lifting arrangements where underwater access, working space, transportation requirements, or load geometry create engineering limitations.

Construction & Materials

The main body is manufactured from high-strength synthetic reinforcement fabric with a durable rubber or elastomeric coating. The reinforcement layer provides tensile strength and dimensional stability, while the external layer protects the structure against abrasion, moisture, repeated folding, and normal contact with underwater surfaces.

Reinforced seams, load-bearing webbing, lifting points, inflation valves, and connection components are integrated into the product structure to provide a defined path for transferring buoyancy forces to the load.

Operating Principle

The operating principle is based on controlled displacement. When compressed air is introduced, the bag expands and displaces surrounding water. The resulting buoyancy acts upward against the submerged load, reducing its effective underwater weight. The operator can control the lifting process by adjusting the air volume and using several bags at different lifting positions.

This provides greater flexibility when the load has an irregular shape, an offset center of gravity, or changing support conditions. For marine construction and recovery work, controlled buoyancy is often required at different stages rather than only at the final lifting position.

Case Study: Buoyancy-Assisted Removal of Submerged Construction Frame

Project: Removal of 18-tonne steel construction frame from coastal maintenance zone in Japan

Challenge: Restricted working area, partially buried frame in compacted sediment and stones

Solution: Multiple Underwater Lift Bags positioned beneath structurally suitable sections with controlled progressive inflation

Result: Successful recovery with controlled movement, reduced mechanical handling demand, and reusable equipment for future projects

Underwater lift bag deployment in marine construction project Lift bag configuration for submerged structure recovery
Technical Specifications
Product Name Underwater Lift Bags
Raw Material PVC coating fabric
Type Cylindrical
Size 500kg, 1000kg, 5000kg, 10000kg, etc
Thickness 0.4-1.2mm, or as requested
Color Yellow, Blue, Black, etc
Density 0.33-0.9g/cm³
Safety Factor 7:1
Tolerances ±0.03 on densities, ±0.2mm on thickness, ±0 to +3mm on width, ±0 to +3mm on length
Model Specifications
Model Buoyancy (kg) Buoyancy (lbs) Diameter (mm) Length (mm) Weight (kg)
HM-ULB01 200 441 500 1,000 5
HM-ULB02 500 1,103 800 1,000 8
HM-ULB03 1,000 2,205 1,000 1,500 11
HM-ULB04 2,000 4,410 1,300 1,500 20
HM-ULB05 4,000 8,820 1,600 2,000 50
HM-ULB06 6,000 13,230 2,000 2,000 66
HM-ULB07 8,000 17,640 2,000 2,600 75
HM-ULB08 10,000 22,050 2,400 2,400 80
HM-ULB09 15,000 33,075 2,600 3,000 110
HM-ULB10 20,000 44,100 3,000 3,000 130
HM-ULB11 30,000 66,150 3,000 4,500 170
HM-ULB12 50,000 110,250 4,000 4,000 220
HM-ULB13 70,000 154,350 4,000 5,700 310
HM-ULB14 100,000 220,500 4,000 8,000 450
HM-ULB15 150,000 330,750 5,000 8,000 660
HM-ULB16 200,000 441,000 5,000 10,000 900
*Note: Other sizes can be customized according to requirements.
Key Features
Reinforced Structural Integrity

High-strength synthetic reinforcement provides tensile strength and dimensional stability for underwater load support. The internal reinforcement carries tensile forces while the external coating protects against abrasion, moisture, and mechanical contact.

High Wear Resistance

Durable rubber or elastomeric coating withstands demanding contact conditions with steel structures, sediment, and rocky seabeds. The material maintains flexibility while providing excellent abrasion resistance for extended service life.

Controlled Inflation System

Progressive air introduction allows staged load reduction and precise buoyancy control. Operators can monitor load response and adjust inflation rates for optimal stability and safety during recovery operations.

Compact Transportation & Deployment

Deflated equipment can be folded for compact storage and transportation. Flexible deployment adapts to various underwater geometries without requiring rigid lifting frames, supporting efficient equipment utilization across multiple projects.

Applications
  • Coastal Infrastructure Maintenance: Removal, relocation, and installation of submerged structural frames and marine hardware
  • Shipyard and Dock Engineering: Movement of submerged steel components and machinery in wet docks and maintenance basins
  • Underwater Construction Component Handling: Installation and positioning of precast structures, steel frames, and marine supports
Why Choose Hongruntong Marine
30+ Years Manufacturing Experience

Extensive expertise in marine product manufacturing with focus on reinforced rubber products, buoyancy equipment, and industrial applications. Established understanding of material selection and structural construction for reliable operational performance.

Advanced Material Engineering

Careful selection of reinforcement fabric, coating systems, webbing, and components based on application requirements. Balanced approach combining strength, flexibility, durability, and handling characteristics.

Rigorous Quality Control

Comprehensive production controls and inspection processes covering material preparation, assembly, reinforcement, seam construction, and final testing. Ensures consistency between manufactured products and technical specifications.

Complete Technical Support

Project-oriented support from product selection through field deployment. Assistance with load analysis, configuration planning, installation procedures, and maintenance guidelines for optimal equipment performance.

Frequently Asked Questions
Can Underwater Lift Bags be used for partially buried loads?

Yes, they can assist with recovery of partially buried loads when properly engineered. Initial buoyancy reduces contact force before additional lifting force is applied. Seabed condition, degree of burial, and load geometry should be evaluated before deployment.

What determines the number of lifting bags required?

Quantity depends on submerged weight, required buoyancy, load dimensions, center of gravity, attachment locations, water depth, and desired load distribution. Large structures may require multiple units positioned at different locations.

Can equipment remain installed underwater long-term?

Suitability depends on project environment, material specification, operating pressure, water depth, and required service duration. Long-term exposure should be evaluated according to specific project requirements with periodic condition monitoring.

What maintenance is required after use?

After recovery: clean of contaminants, allow to dry, and visually inspect body, seams, lifting straps, connection points, valves, and inflation components. Store in dry environment away from sharp objects, excessive heat, and direct sunlight.

Can connection arrangements be customized?

Yes, connection configurations can be adapted for specific lifting methods and load geometries. Options include reinforced lifting straps, specified connection points, and custom inflation arrangements based on project requirements.

Underwater lift bag in operational configuration Marine construction using lift bags for buoyancy control Industrial lift bag application in underwater project
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Get in touch with us
Contact Person : Mr. William Lau
Tel : +8618910539783
Fax : 86-10-89461910
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