Buoyancy Lift Bag System

Overview

The Buoyancy Lift Bag System is a versatile underwater lifting range for salvage, refloating, buoyancy support, and underwater installation work. Three bag types — parachute, cylindrical, and pillow — cover working loads from 100 kg to 50 t, and every bag is built from 1.2–1.4 mm PVC-coated polyester or TPU with high-frequency welded seams, abrasion- and corrosion-resistant construction, and industrial webbing rated to a nominal 7:1 safety factor. Single bags handle focused lifting tasks; multiple bags can be combined into a lifting system for heavier loads.

Model Overview

Parachute Lift Bags

Open-bottom parachute lift bags deliver stable vertical lifting with controlled venting, covering most light- to medium-duty underwater lifting and rescue operations — from 100 kg up to 50 t. Top lifting points allow the load to be transferred to large lifting equipment once it reaches the surface. A manual pressure-relief valve with lanyard and a clearly marked inversion-line attachment point allow dynamic buoyancy adjustment during the lift. Open-bottom or enclosed versions, multiple colors, and multi-bag combinations for heavier loads can all be supplied.

Cylindrical Lift Bags

Cylindrical lift bags are the workhorse for vessel salvage, pontoons and supports for floating structures, and seabed projects such as underwater pipeline installation. The enclosed cylindrical shape provides vertical upward buoyancy — its primary advantage for raising submerged vessels. In shallow water, two bags can be connected through the high-strength webbing at their ends or sides using bow shackles: once inflated to the relief setting, they serve as pontoons for towing a stranded vessel back to open water. Automatic pressure-relief valves are fitted as standard, with capacities from 100 kg to 50 t and custom colors available.

Pillow Lift Bags

The pillow lift bag takes its name from its distinctive shape. Its design focuses on lifting loads in deep water through a single lifting point, providing adaptability in operating conditions that other bag shapes cannot offer. It is generally used for salvage, diving, and buoyancy-assistance work at water depths of at least 5 m. Automatic pressure-relief valves are fitted on the side, with an optional manual pressure-relief valve with lanyard. Capacities run from 100 kg to 4 t, with custom colors available.

PRV = pressure-relief valve. Dimensions are nominal and shown in centimetres. Valve quantities and attachment details can be customized for the intended lifting plan and local operating procedure.

Complete Lift Bag System

A complete system combines inflatable lift bags with the surface and underwater supply equipment needed to run them: air cylinders, an air compressor, a triple-gauge regulator, adapters, inflation hoses, and an adjustable inflation control panel.

• Dual supply — the control panel provides two high-pressure inlets for switching between portable cylinders and a compressor supply.
• Synchronized inflation — two low-pressure outlets inflate two bags simultaneously; linked panels can support multiple groups.
• Controlled ascent — adjustable flow control helps manage ascent speed and reduce the risk of uncontrolled rapid lifting.

Construction and Included Components

Every bag is made from 1.2–1.4 mm PVC-coated reinforced polyester mesh fabric (1.4 mm on parachute types), with high-frequency welded seams that resist abrasion and corrosion in freshwater and seawater. Standard equipment supplied with each bag includes:

• Load-bearing webbing — industrial-grade polyester, nominal 7:1 safety factor
• Bow shackles and heavy-duty lifting ring — galvanized, 4:1 safety factor
• Inflation inlet — plastic base with 3/4 in ball valve and male air-hose quick-connect fitting
• Automatic pressure-relief valve — set at 15–25 kPa
• Pull-cord pressure-relief valve — top- or side-mounted, 15–25 kPa
• Repair kit — PVC adhesive and PVC repair patches

Key Features

• Lightweight and foldable design — easy transportation, storage, and rapid mobilization between job sites
• Fast inflation and deployment — from 40 s on compact models
• Adjustable buoyancy control — automatic and pull-cord relief valves for dynamic lift management
• Modular combinations — multiple bags join into a single lifting system for heavy salvage
• Suitable for freshwater and seawater — corrosion-resistant materials throughout

Use Cases

• Underwater Salvage
• Vessel Refloating
• Offshore Engineering
• Pipeline & Cable Installation
• Diving Operations
• Marine Cleaning & Inspection
• Shallow & Deep Water Lifting

Customization

Custom capacities, colors, valve configurations, and connection details are available. Tell us the load, working depth, and lifting method, and our engineering team will propose a bag combination and inflation setup matched to your project — together with a project-specific quotation and drawing.