The Liebherr offshore crane division installed a board offshore crane, type BOS 35000 on the heavy lift barge “Giant 7”. The state of the art offshore crane will be used for wind plant installation in the Baltic Sea region.
The entire project starting from design through manufacturing to final assembly and testing has been conducted in the company’s production site in Rostock, northern Germany.
The crane was especially developed for the use on the “Giant 7”, a heavy lift barge. On arrival at the Liebherr Rostock facility in January, the crane installation started immediately.
The biggest challenge when assembling heavy lift giants like the BOS 35000 is the handling of oversized parts. The lattice boom is 78 meters long. Its weight amounts more than 250 tonnes. With 390 tonnes, the machinery house is even heavier.
Because of these dimensions two Liebherr mobile harbour cranes, type LHM 600 were necessary to assemble the components. Installation of steel ropes, hydraulics, electronics as well as the main hook completed the crane.
“The dimensions both in weight and size are also for us, far away from being usual. For this reason we attach the greatest importance to safety during assembly. We had 25 experienced engineers and technicians constantly occupied with the project. Including work preparation, their task took around 5000 working hours”, comments Gordon Clark, Liebherr Sales Director Offshore Cranes.
The assembly of the BOS 35000 on the “Giant 7” took 41⁄2 weeks. After this period the final phase started. Before delivery, every product goes through an extensive testing process.
Testing includes measurements of luffing and hoisting speeds, boom movements as well as the static and dynamic behaviour of the crane structure. The stability and reliability is tested by lifting weights up to 660 tonnes – 10 percent more than the
regularly working load. The tests are fulfilled in accordance to all relevant offshore regulations.
Assembling and testing the BOS 35000 on the “Giant 7” could be finished after just 6 weeks. The barge is currently on the way to its new operation site in the Baltic Sea.
The BOS 35000 will be used for installing offshore wind parks.