For permanently moored floating objects, such as FPSOs, it is important from a safety perspective to maintain the correct mooring line tension. Identifying that the conventional methods for achieving this have several disadvantages, Royal IHC has developed a unique subsea tensioning tool that will bring numerous benefits to the offshore oil industry.

Our portable subsea tension tool (STT) will be used to tension the mooring line after hook-up, where it will be deployed and operated from a vessel. After tensioning, the tool can be retrieved by the vessel to be used on another mooring line.

Key benefits

With this tool, we are introducing a method for tensioning mooring lines that enhances safety, reduces initial capex expenditure and also minimises operational costs during re-tensioning. 

Safety is enhanced by the reduction of corrosion issues and fatigue commonly suffered by the top chains in mooring lines. Cost reduction is another major benefit, as the STT negates the need for expensive deck equipment, that requires a schedule of regular and often expensive maintenance. 

Lightweight alternative 

The advantage of our tool is that what remains in the mooring line after tensioning is a standard certified H-link, which adds almost no extra weight. Most other underwater tensioning solutions in the market leave quite a lump of steel in the mooring line, which we don’t have with our solution. In addition, using a standard H-link for reconnection is also the reason that the tool can be used for re-tensioning existing mooring lines.

Next steps

The design for the STT prototype is now ready for production and can be made available to the market. Initially, we intend to offer the STT as a rental tool, although it will also be possible for operating companies to purchase if they prefer. 

In addition to the offshore oil market, we have identified potential opportunities for the tool to be used in the renewables sector. Whatever the future holds for the STT, the development of this unique equipment has put the innovative capabilities of IHC firmly in the spotlight. 

Written by

Maurits van Wezel
Research & Developer

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