Ironically, when installing a wind turbine, wind makes things difficult. First you have to lay the foundations, then build the towers and finally fit the huge rotor blades. This would be almost impossible to achieve from a lurching ship. Wind farm contractors therefore deploy special ships known as jack-up vessels. They navigate to the construction site and dig their legs into the seabed when they are in position. Depending on the model, they have four to six supports, each over 80 meters in length. Once the feet are anchored, the ship is propelled out of the water by enormous cogs. A few days later, when its work is done, the ship is lowered again.
Maintenance under extreme conditions
Maintaining the jack-up mechanism is an essential but complex process. After all, the legs are exposed to immense forces. If material fatigue occurs far out at sea, the consequences can be catastrophic. This is why it takes up to six people to lubricate the pinion on each leg when installing a jack-up system—sometimes in life-threatening conditions. “It is virtually impossible to apply the right amount of lubricant. Jacking systems are usually over- or under-lubricated,” says Markus Boose from SKF. In such conditions, metal meets metal, which can reduce the material’s service life. This often occurs when the ships have to be raised and lowered every few hours, as is the case when installing offshore wind turbines.
Reduced costs, prolonged service life
One solution to this problem is an automatic spray lubrication system that applies the right lubricant by using nozzles. This system always apply the correct amount of grease, at the precise angle to the teeth. Such automatic systems are easy to maintain and are already used in other industries, such as the cement industry, where they help keep the huge mills and kilns running by lubricating their open gear tooth flank. “Ship operators can reduce their lubricant costs and extend the service life of the lifting mechanism,” says Boose. Even more importantly, they keep their crew safer.
The automatic lubrication system for jack-up rigs supplies a predefined amount of grease to the friction point. This helps to save costs, manpower, and maintenance resources on jack-up vessels.