DAVI iRoll eXtreme Control System : Setting new standards in off-shore foundations manufacturing

By Dario Mulazzani, DAVI Product & Market Specialist Wind Energy & Heavy-Duty Division

Figure 1 Off-shore foundation designs

Located in such a dynamic and extremely powerful element as the sea, foundations represent one of the main elements of any off-shore wind farm which typically accounts for over one-fourth of the total equipment cost.

Foundations must support the wind turbines by absorbing all the forces and loads and providing a safe and stable base: different designs can be selected according to technical and economical requirements such as seabed depth and fabrication complexity (Figure 1).

Defining the right typology of foundation can have a huge impact on both the economic and the technical side of any off-shore wind project.

Figure 1 Off-shore foundation designs
Figure 1 Off-shore foundation designs

But how are these critical components manufactured?

Typically, foundations are comprised of large steel plates jointed together and rolled into cans and cones; these workpieces are then assembled on so-called “growing” lines where they are welded into larger structures.

In the case of Monopile Foundations, such structures can reach up to 120m in length and 3500 ton in overall weight. With plates thickness often exceeding 140mm and increasingly large diameters (up to 13-15m) it becomes critical to minimize the amount of circumferential welding required to grow the overall length, leading to the selection of increasingly large plates (up to 4.5m in width, with weights often exceeding 150 tons each).

Conversely, O&G derived foundations (such as tripods and jackets) are comprised of thick (up to 120mm) and small diameter (1.3-2.5m) cylindrical cans jointed together to form relatively complex structures.

Fabricators engaged in the manufacturing of such heavy-duty off-shore foundations will need to face and overcome three main manufacturing challenges:

  • Increasing ratio between forming diameter and plate thickness (D/T) due to monopiles large conical and cylindrical sections diameter. High D/T leads to workpiece instability which, if not properly managed, generates undesirable deformations depleting the overall rolling accuracy.
  • Large diameter conical sections with angle up to 14°: commonly used to transition between monopiles bottom and top sections (having increasingly different diameters), the resulting cone developments are heavily unbalanced with a side and longitudinal footprint often exceeding 16m and 40m respectively for a 13m diameter.
  • Extremely low D/T and tight roundness tolerances: manufacturing of jacketsstructural pieces such as legs, braces and piles is particularly challenging due to extremely low D/T ratio (thick plates formed into small diameters) combined with very tight roundness tolerances imposed by the downstream assembly process.

Together with dedicated heavy-duty feeding and handling equipment which is continuously being developed and updated, DAVI, with its new top-of-the-range control system iRoll eXtreme brings to the market exclusive features to ensure that Fabricators entering the DAVI World are provided with the most advanced hardware and software allowing them to maintain competitiveness in a fast changing and dynamic environment, requiring more and more challenging workpieces to be manufactured every year.

For instance, thanks to the interactive pre-production 3D simulation, the Operators will be able to review the whole Rolling Line actuation sequence, preempting potential issues (collision between accessories and workpiece, accessories operating range, etc.). This is particularly relevant for off-shore foundations parts requiring a complex line to be fabricated, such as large diameters Monopiles (as mentioned above).

Moreover, complete Line automation (machine and accessories) together with self-learning Artificial Intelligence-powered programming, lead to repeatable cycles even with very large and heavy plates, minimizing idle times and unnecessary and costly parts re-working.

Due to the very low D/T ratio characteristic of Oil & Gas derived foundations (jackets, tripods, etc.), cans are particularly “hard” to be formed and often multiple rolling passes are necessary to reach the final diameter (multi-pass process). In a conventional setup, skilled operators would be required to achieve the final shape by determining the required number of passes relying solely on their experience.

Thanks to iRoll eXtreme advanced programming features (multi-pass programming) and enhanced assisted manual modes (multi-pass aid), Operators will be able to rely on the software instead.

In addition, due to the very tight tolerances, cans often have to be re-rolled to improve their final shape. Once a cylinder is formed and its edges welded, the rolled piece is placed back in the machine which rotates it and exerts force to improve roundness. To properly execute the additional operation, the plate has to initially be rolled into an apple shape to allow for the re-rolling process.

Traditionally, skilled operators would be required to achieve the right apple shape with a “trial-and-error” approach.  Similar to the multi-pass operation, the iRoll eXtreme greatly improves the achievable automation by generating an apple shape automatically or semi-automatically within the tolerances specified by the end-users (ASME Tolerances Compliance System).

Thanks to these and other exclusive features, DAVI newest top-of-the-range control system, iRoll eXtreme, sets new standards in the manufacturing of off-shore foundations parts.

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Note: The opinions, beliefs, and viewpoints expressed in this article do not necessarily reflect the opinions of Offshore WIND.