The joint venture of Montanhydraulik and Dutch subsidiary Muns Techniek in the offshore sector has completed the development of the entire hydraulic lifting system for the latest Hochtief Solutions jack-up ship Vidar. The jack-up vessel, currently in construction at the Polish shipyard Crist, will be used for both the company’s construction projects and also for charter contracts.
The ship converts into a jack-up platform following the hydraulic lowering of four movable supports that measure 90m in length and 4.8m in diameter. The jack-up system can lift a total of 25,000t out of the water. It consists of 48 corrosion-resistant cylinders, the respective bolting units and guide frames and the corresponding electrical control system.
Montanhydraulik managing partner Dr Peter Lipphardt said: "The design requirements for this job are extremely high. This not only applies to the functionality of the legs, but also to the reliability of the entire jack-up system, including the hydraulic cylinders we deliver."
Synchronous control for smooth lifting and lowering
The special feature of the hydraulic construction is based on two movable guide frames per support, positioned opposite to each other. Six cylinders move via the frames, each of which has a diameter of 800mm and a length between 7.4m and 10.4m, weighing around 22t. Their movement is regulated by synchronous control. Muns Techniek developed the control system in order to ensure the synchronous lifting and lowering of the four supports via the necessary lift, without the platform having to be stopped for the bolting procedure.
The special jack-up ship, with a length of 136.5m and a width of 41m, travels at a speed of up to 12k and can transport up to 6,500t. A 1200t crane makes up the standard equipment for assembly and installation of the foundations and wind turbines. The ship is the fourth large vessel owned by the Hochtief Group. Muns Techniek and Montanhydraulik previously supplied the hydraulic units including cylinders and control systems for the jack-up platforms Odin and Thor.