SPS was used for spudcan reinforcement on the MPI Resolution, which transforms from a ship to a stable platform, at heights ranging from 3m [10ft] to 46m [151ft] above the surface of the sea, by deploying its six legs and ‘spudding’ down on the surface of the sea. At the base of each leg is a wide hollow tank – or a ‘spudcan’ – that has to be capable of withstanding huge loads from above as well as upward point loads from rocky seabeds.

These spudcans provide an increased bearing area on the sea bed to spread the load and prevent the legs from penetrating the soil when located on station. A significant risk to safe and reliable vessel operation is the presence of large granite boulders deposited on the sea bed after the last ice age. Boulders more than 1m in diameter can cause concentrated loads greater than 390t on the base of the spudcan. Without appropriate reinforcement, these loads can cause major indentations and serious damage to the internal structure of the feet.

To reduce operational risk it is routine practice to survey site locations and clear any oversized boulders before the vessel “spuds in”. This minimises the risk of damage, but is an expensive and time consuming process. However, by strengthening the underside of the spudcan to withstand loads from large boulders, the site clearance becomes faster, safety is increased and operational costs reduced.

MPI Resolution’s operators, MPI Offshore, had a limited window of opportunity for carrying out the 360m² strengthening. Conventional crop-and-replace with thicker steel was not an option. Only SPS could fulfil the strength requirements and be fitted within the docking schedule of less than four weeks. After completion of the steelwork by the shipyard, the SPS injection process took only four days for all six legs.

The enhanced strength of the SPS spudcan reinforcement was demonstrated by SPS Technology using full non-linear Finite Element Analysis (FEA) to replicate the maximum loads and their effect on the structure. The design calculations were examined and verified by DNV using their classification note 30.11. Onsite at Damen Shiprepair Dunkerque, the SPS installation was witnessed by the local DNV survey team, who verified that the installation process was carried out in accordance with DNV’s guidelines for SPS construction.

More information about this remarkable vessel can be found at MPI Offshore, Damen Shiprepair and Conversion, as well as Wikipedia.