Dutch Conbit Achieves New Milestone

In the beginning of September 2011 Seajacks awarded Conbit with the contract to engineer a solution for the handling of the monopiles for the Meerwind project. One year later the new jackup vessel was supplied, finished its first assignment and is equipped with all tools for its first big job. This project completion forms a new milestone for the Conbit team.

As with a lot of engineering jobs this one started off with an idea. The idea covered the use of SPMT’s to move monopiles from their seafastening into the fire line. The unique seafastening concept gave Seajacks the confirmation that Conbit was the right party to complete the project. After the summer the agreement was signed and the Conbit engineers started with the feasibility and the basis of design. The experiences gathered in the offshore oil- and gas industry were of great benefit during the early stages of this project.

Engineering

During the feasibility study it became clear that the dragging loads during transit required positioning of the monopiles three meters above deck level. This was required because of the weight of the monopiles (between 500 and 670 tonnes) in combination with the maximum significant wave height of 2 meters as the design criteria. The grillages were adjusted to this parameters. An unforeseen benefit is that the crew can walk freely underneath the monopiles.

As indicated during the proposal period Conbit advised to use a method of friction to hold the monopiles in their grillages. Each monopile would be kept in position using grillages with two saddles on top. Initially the friction was obtained by a sort of lashings. Four of these lashings were used to pull down one saddle, which laid on top of the monopile. By connecting two lashings on each side of the monopile and pulling them together, it should be possible to get the required load of 100 metric tonnes in each lashing by hand. At a later stage this system proved to be unable to fulfill the requirements and a different system was implemented. The improved system involved the same lashings, but the load would be generated using a hydraulic tensioning system.

Procurement

In projects like this it is often cost and time efficient to let the engineers be in charge of the procurement as well. Quotations can be requested in early engineering stages and engineered solutions can be modified throughout the process to improve the cost-quality relation. This approach has a lot of advantages in comparison with a more traditional approach, which required the engineer to be finished before the procurement process is started.

Seajacks awarded Conbit with a procurement contract for the equipment designed by its engineers. The procurement process was started early in the project. Qualified suppliers were selected. In total 18 subcontractors were contracted. The Conbit team coordinated the procurement process and managed to transport the items in time to the desired location.

Construction

After all factory tests were successful and to the satisfaction of the client the equipment and materials were transported to Amsterdam. At the Shipdocks yard in Amsterdam the Zaratan jackup vessel was commissioned. Conbit’s and all other equipment were installed onboard within a very short time period. Final tests of the equipment were carried out on board the Zaratan. On Monday morning the 27th of August the Zaratan left to Cuxhaven, where it would start its first big job. Seajacks was awarded a contract to install 78 foundation piles for the Meerwind offshore wind park. The Meerwind Offshore Wind Project consists of 80 Siemens wind turbines with a power output of 3.6MW each.

[mappress]

Press Release, October 30, 2012