Lifting over launching
The typical steel-framed jackets required for offshore structures need to withstand environmental forces and the weight of heavy topsides. In some cases they can be huge, and in the past, these structures required a 'launch installation' due to their weight. These operations involved launching the steel jacket equipped with floatation devices from a launch barge into a floating horizontal position, where it could then be uprighted and installation finalized.
Heerema has various barges suitable for launching and continues to support these installation methods. However, with the introduction of Sleipnir, we can lift these gigantic jackets instead of launching them!
What are the advantages?
The main advantage for clients is that the jacket will be much lighter as we will remove the need for the required buoyancy tanks to ensure launching operations are a success. In addition, by lifting the jacket, the operation becomes more straightforward with the ability to use both cranes to lift the jacket directly from a barge. This action means there is greater predictability and less weather sensitivity for the project.
We want to help clients lift jackets instead of launching wherever possible, and to do that, we get involved early to assist in FEED studies and use our Simulation Center to assess all project aspects. In terms of lifting capacity, we have Sleipnir, the world's largest semi-submersible crane vessel, with two cranes that have 10,000 metric tons lifting capacity each.