SECTION SPONSOR OPERATIONS & MAINTENANCE
PROJECT MANAGEMENT – THE PROCESS
As the operator selected Great Yarmouth outer harbour as the most beneficial place for the construction of these anode banks, 3sun Group was chosen to manage the project. The Group assembled anodes on to specialist frames designed to be loaded on to cargo vessels for deployment to the seabed, with multiple banks required for each of the wind turbine structures.
Prior to the construction of the anode banks, the individual anodes were delivered to the harbour by vessel. The offloading process required four anodes to be lifted at one time for storage at the quayside. This was a challenging process which required a total of 712 lifts but was executed efficiently and within the necessary time scale.
The assembly team were responsible for lifting the single anodes into their correct position on the anode bank to form layers on the transportation frame. Each anode was lifted individually and placed in the anode frame which resulted in a total of 2484 lifts.
The process involved using suitable rigging techniques to fit the correct length piles for the transportation frames and ensuring the single anode lifting beam was fitted securely and correctly to the single lifting point adapter.
The completion team then connected steel wires and bonding cables to complete the anode bank. This involved installing four steel wires per anode bank layer to clamp mounts which were installed to maintain the position of the anode when the anode bank is lifted offshore. Cargo straps were utilised to secure the loose ends of the steel wires to the piles of the transportation frame. Once the bonding cables and steel wires were connected, the anode banks were tested for continuity as part of the final inspection process. In total, 62 frames were filled and connected then lifted from the quayside to the cargo vessels.
ADDITIONAL CHALLENGES
As well as the large volume of lifts required, many additional challenges were faced during the project. As the next stage of the project involved using ROVs to install the connection between the anode banks and the wind turbines, 3sun Group had to ensure that the subsea connector on the anode bank would be secure during offshore lifting. However, it was imperative that the securing method would be easy to release by ROV operators. In addition, the securing method must not produce any waste offshore when released, so as to prevent any environmental damage.
The simplest method would have been to use large zip ties and secure the bonding cable to the anode. This would have prevented the bonding cable obstructing operations when lifting and would also have allowed an easy release. However, the ROV cutting the zip tie would have resulted in hundreds of zip ties abandoned in the North Sea and an unacceptable level of environmental waste.
SOLUTION
As a solution, a stainless steel wire rope sling was constructed and installed. This allowed the cable to be released, but with the sling remaining on the anode due to a separate attachment point. Stainless steel was the preferred material for the sling to prevent corrosion and the release of further waste into the sea.
Additionally, it was imperative to ensure the different types of anode banks were built and stored separately. The frames were to be loaded in rock dump and non-rock dump configurations which were vital to the transportation and deployment processes. Rock dump anode banks were configured with taller feet to have the ability to clear any cables on the seabed and so were to be easily identified for transportation to the specific vessel required for this method of deployment.
AHEAD OF SCHEDULE
Despite the first vessel arriving earlier than expected, 3sun Group achieved an accelerated time schedule throughout the project, resulting in significant cost and time savings for the operator. Shipment deliveries were consistently more efficient than estimated throughout the project, which allowed the final shipment to be delivered approximately one month ahead of schedule.
3sun Group Click to view more info
www.windenergynetwork.co.uk
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EAST OF ENGLAND SPOTLIGHT ON
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