A jacket structure has a much more complex geometry than a monopile foundation. Essentially, a jacket consists of three or four legs diagonally and horizontally braced against a transition piece in the center. The legs are also interconnected with bracing to provide the stiffness required. Depending on the height of the jacket, the number of cross bracings normally varies between 3-5. At the end of each leg, there is also a pile transition piece to connect to the straight piles that are being piled into the sea bed.
Due to the geometry of the jacket, its manufacturing process cannot be automated to the same extent as a monopile production process. A basic condition for successful welding automation is the accurate cutting of the individual structure components. The remaining joints have to be welded manually or semi-automatically using, for example, orbital welding equipment.
The primary welding methods are SAW and GMAW. The manipulators used can be standard column and booms, utilising SAW welding process, and robots that use the GMAW process.
High Level of Automation
The share of the cost of the foundation relative to the complete wind turbine installation is considerably higher than with onshore foundations. It is extremely important to optimise every part of the foundation production flow to minimize all associated costs. PEMA offshore foundation manufacturing lines are always specially engineered for the manufactured foundation type, ensuring the highest reasonable automation level. Therefore, the productivity and quality produced by PEMA solution is superior to that of other manufacturing lines.
Robotised Node Welding Station for Jackets
Automatization of node welding is one possibility to increase efficiency in jacket production. Demanding weld shapes can be handled with parametrized robot programming and laser-based seam tracking.
Production Lines for Jacket Legs and Piles
Jacket legs and piles are made from relatively thick material but have smaller diameters than other offshore foundation structures. PEMA has specialized solutions with submerged arc welding.