Seaflex Limited


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Marine Buoyancy Products and Water Filled Test Weights

Since 1987, Seaflex Ltd has been at the very forefront of air lift bag and water load bag technology.

Seaview Road,
PO31 7US,
Isle of Wight,
United Kingdom
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We are a trusted partner to the offshore oil and gas, salvage, shipping and defence sectors, offering as we do a vast range of off-the-shelf products to address the most demanding of buoyancy and load testing challenges. And when a client of ours has a challenge which cannot be solved off-the-shelf, then we draw upon our decades of expertise in the areas of buoyancy and ballast to provide them with a customised solution which will best meet both their operational and their financial requirements.

We know that our clients are reliant upon us and our ability to produce and deliver products which they can put their complete trust in. This is why no other manufacturer has put in place a more comprehensive testing and certification regime than ours. Seaflex WaterLoad bags have been drop- tested at the UK’s TÜV National Engineering Laboratory (NEL) and gained type test accreditation at the 6:1 FoS to meet LEEA Guidance 051. Our air lift bags are all fully compliant with IMCA D-016, AND have been tested to a minimum SWL of 5:1 per IMCA requirements. We also have certified ABS Product Design Assessment (PDA) across our main product ranges.

We also know that some of clients will wish to buy this type of equipment whereas others will prefer to hire it. So we offer both business models, and our hire option is supported by the largest combined fleet of buoyancy and ballast on the planet – placed with Unique group offices and rental partners in strategic locations right around the world.


The Seaflex range of open bottom (or "parachute-type") air lift bags is available in capacities up to 50t, to support and lift loads from any depth. While their single point attachment is ideal for lightening underwater structures such as pipes and templates, their main application is for lifting vessels and other loads from the seabed to the surface.

Seaflex ALB on FPSO moorings retrieval project, Mediterranean Sea.
Seaflex IBUs aiding installation of Baku-Tbilisi-Ceyhan pipeline.
Seaflex MBUs being deployed off the stinger of the Allseas Solitaire.
SeaSerpent in action, London Array project.
300t of Seaflex WLBs testing an A-frame.


Whether being layed off the back of a stinger or towed out from shore, there is no easier and more cost-effective way of supporting a pipeline at or near the surface during installation than by using Seaflex enclosed buoyancy units. Our MBUs are a new development, unique in the market, which are designed for single-pont attachment – so allowing them to be speedily rigged up and to be used at any angle to the load.


Instead of using multiple floats to support a submarine cable during installation in shallow water, the SeaSerpent is a continuous inflatable tube attached to the cable at 1.2m spacing. While its support and control of the cable is excellent, perhaps its most advantageous characteristic is the operational flexibility it allows the installer. The easy launching procedure is followed by a progressive and controlled sinking sequence, which can be started, slowed, or reversed by simple surface control without divers.

While Seaflex are the major worldwide providers of individual inflatable buoyancy units for pipeline installations in shallow water, there are special cases where the long tube Kraken buoyancy system can be used to greater advantage. The patented system consists of a PVC coated fabric attached to a pipe at 1.2m intervals to create a continuous buoyancy member, which produces very low stresses in the pipe. The coated fabric tube is tough and resilient and with the close spaced fixings, each attachment is only under a very small load.

Kraken’s advantage over conventional IBUs is its ability to float pipes in very shallow water, which can in sometime dramatically reduce dredging costs, and its low frontal profile for long surface or mid-water tows.


With a track record spanning more than 15 years and taking in many of the biggest names in lifting, testing and inspection worldwide, Seaflex WaterLoad test weights have proved themselves time and time again to be:

  • Safe
  • Reliable
  • Versatile
  • Easy to use and to maintain
  • Excellent value for money

Made from High Tensile Trevira® Polyester 3/3, coated with heavy duty UV stabilised PVC coating, and with integrated slings and fittings which comply with relevant British Standards and LEEA guidelines, our WaterLoad test weights are built to last. High quality performance, robust fabrics, reliable RF welded seams and versatile filling/discharge arrangements have made Seaflex WaterLoad bags the first choice for an ever-increasing numbers of test houses around the world.

A range of bag capacities from 1t to 50t allow Seaflex WaterLoads to be used singly or in clusters to produce test loads of up to 150t in a single cluster. Multiple clusters can be utilised for larger test loads.


Building on the success of the Seaflex WaterLoad™ range of test weights, and making use of the same top-quality design and construction principles, Seaflex has introduced a versatile multi-unit system for testing lighter, enclosed loads with access issues such as lifeboats and elevators.

Outstanding performance, robust fabrics, reliable RF welded seams and general ease of use have made our LTS the first choice for ever-increasing numbers of lifeboat testing and certification houses around the world.

The Seaflex LTS consists of a series of 375kg water bags coupled to a remote filling and discharge manifold. This allows the required load to be safely applied in spaces where traditional solid weights are difficult, and potentially dangerous, to position.

The standard system comprises of a complete kit, supplied in a ISPM 15 compliant timber transit box (fork lift or crane sling) containing all the equipment required to test up to 6t in lifeboats, platforms and other structures. The kit comprises 16 x 375 kg test bags (sufficient to test an 80 man lifeboat), a calibrated water meter, a 1 x 6 way manifold with quick connectors, 6 x colour coded delivery/discharge hoses, and an air driven double diaphragm pump with suction tube & delivery hose that can fill up to 7 bags simultaneously and which is rated to work in hazardous environments.

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Seaflex Ltd
Seaview Road
PO31 7US
Isle of Wight
United Kingdom

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