On- and Offshore

In order to ease the supply bottleneck when building their own wind farms, a German company for renewable energy placed an order for two special ships of the same design with the Korean shipyard Daewoo Shipbuilding & Marine Engineering.

After completion, the construction ships with a length of 109 m and a beam of 40 m can transport as well as erect up to four offshore wind turbines of megawatt classes 5 and 6, including the foundations, even under rough offshore conditions. This enables the company to gain significant time and cost benefits.

The ships can be positioned at sea with centimetre accuracy by means of satellite. They can work in depths greater than 40 m, and are therefore ideally suited for the installation of the planned offshore wind farms.

For the ships, Montanhydraulik and Muns Techniek jointly supply the complete hydraulic lifting system, consisting of cylinders, bolting units, and guide frames, including the associated electrical controls.

What makes the design of the ships unique are the two synchronously extensible frames for each pillar, whose movement is governed by a synchronous control system developed especially for this order. This makes it possible to raise and lower the four pillars synchronously using the necessary lift, without the platform having to be stopped for the bolting process.

Through the hydraulic lowering of four movable legs with a length of 90 m and a diameter of 4.80 m, the ship becomes a lifting platform. The lifting system raises a total weight of 25,000 t from the water. It consists of 48 corrosion-resistant cylinders from Montanhydraulik, the necessary bolting units and guide frames, and the associated electrical controls.

The hydraulic design is distinguished by two extensible opposed guide frames for each leg. Their movement is governed by a synchronous controller. Muns Techniek developed the controller in order to ensure synchronous raising and lowering of the four legs using the necessary lift, without the platform having to be stopped for the bolting process.

The legs of the jack-up ship are lowered to the sea bed with a stroke speed of 1 m/min. For this, the hydraulic system provides not only the stroke function, but also gives the ship a high imperviousness to impacts. As soon as all four legs make contact with solid ground, the ship lifts itself out of the water.

The special jack-up ship, with a length of 136.5 m and a beam of 41 m travels at a speed up to 12 kn, and can transport up to 6,500 t. A 1,200 t crane forms part of the essential equipment for assembly and installation of the foundations and wind turbines for setting up offshore wind farms.

The LHM product range includes flexibly operable mobile harbour cranes designed for various applications, ranging from container transfer to the transport of containers, bulk materials, and general cargo. The largest mobile crane in the range, the LHM 800, lifts heavy loads of up to 308 tons.

The LHM consists of a slewing boom crane equipped with a chassis, and can perform the three main movements: Slewing, luffing, and lifting. The boom is powered by a hydraulic differential cylinder.

A further special feature, which specifically fulfils the safety requirements of the crane manufacturer, is the position of the luffing cylinder. This is positioned above the boom. This prevents cylinder damage which could arise from swinging loads or from high-stacked containers on board. Here too, the cylinder technology comes from Montanhydraulik.

For Montanhydraulik, the outstanding quality of our own products is a permanent and ever-present goal. In order to be able to fulfil this requirement at all times, Montanhydraulik possesses extensive test and quality inspection capacities, as well as the necessary expertise of our employees.

The test and quality inspection capacities include two combinable 25 ton cranes, sufficient working space to turn and test 30 metre long cylinders, and stable structures for optimum working and storage conditions. In addition, glass windows in walls and ceiling provide effective natural lighting.

In addition, the available capacities and equipment allow us to be very flexible, in order to perform final acceptance for very large lot sizes (for example 16 offshore cylinders in a single acceptance test). Here, the final acceptance takes place through the approval and fulfilment of the test standards of DNV, ABS, China Classification Society, Lloyd’s Register, Bureau Veritas, RINA and/or TüV.

In addition, Montanhydraulik has developed and built its own test rig, which enables vertical testing of friction-sensitive cylinder systems. Especially for cylinders used in the offshore sector, this method of quality inspection represents an important and meaningful test process for quality inspection.

Designed to the most varied customer requirements, and fulfilling the specifications of the classification companies, we manufacture fully piped and tested hydraulic aggregates.

The electro-hydraulic high-performance aggregates for jack-up ships are equipped with soft starters and controlled by means of a PLC.

Technical data:

• Weight: approx. 4,000 kg
• Dimensions: 3,500/1,400/1,500 mm
• Pumps (2x)
• Axial piston pumps with load recording
• Flow rate according to customer requirements
• Nominal pressure: 300 bar
• Performance of electric motor: from 419 kW to 640 kW