Monopiles &
Transition Pieces
Precision milling of large-diameter on- and offshore flanges to ensure structural fit, bolt integrity, and long-term reliability.
Support structures and flanges
Monopiles &
How It Works Precision for large-diameter
Precision for large-diameter
Monopiles and TPs
When monopiles and transition pieces are welded to the structure during manufacturing, the heat input can cause twisting and bending in the flange. Sometimes the result is flatness outside the tolerance. This is increasingly challenging, especially in offshore wind turbines where the flanges for jackets, monopiles, transition pieces and bottom tower sections are becoming ever larger while tolerances are being tightened.
With our proprietary precision machine, “Goliath”, fine tolerances can be achieved by post welding milling, meeting the required structural fit. Goliath is our flange milling system, developed to achieve sub-millimetre flatness on large-diameter monopile, transition piece, and tower flanges. Designed for the next generation of offshore wind structures, it delivers controlled tolerances, repeatable quality, and reliable bolted connections at scale.
Machining is in most cases faster than traditional methods like heat straightening while the achievable tolerances are much better.With global flatness tolerances of 1 millimeter and local flatness tolerances of 0.5 millimeter for an 8-meter flange, our Goliath machine offers industry leading tolerances.
Our fully automatic CNC-controlled machine can mill flanges of up to 10-meters in standard configuration and can be configured for diameters up to 12-meters. The fine tolerances allow designers to create smaller diameter flanges that offer the potential to use maintenance-free bolt connections, which ultimately reduces both CapEx and OpEx for the the wind turbine manufacturers.
Technical Specifications
Typical duration 2–7 days on site
Diameter range Up to Ø10,000 mm
Flatness Customer/OEM specification
Certification ISO 9001
Equipment Mobile flange milling system
Structures Monopiles, TPs
Expected lifetime Design lifetime equivalent
ISO 9001OFFSHORE READYLARGE DIAMETERSCNC CONTROLLED
Reduced Lifecycle Costs Improved flange flatness helps reduce bolt-related maintenance, corrective actions, and long-term operational costs.
HSE ADVANTAGES If combined with precise bolt tensioning methods, the precise flange tolerances achieved with Goliath can help reduce the need to retighten bolts and eventually lead to maintenance free connections – reducing OpEx and improving Health, Safety and Environment (HSE).
Repeatable Manufacturing Quality Fully CNC-controlled machining replaces manual correction methods with a predictable and repeatable production process.
Built for Offshore Scale Goliath machines monopile and transition piece flanges up to 12 metres in diameter, supporting the increasing size and complexity of offshore wind structures.
How it works
Our process
01
Quotation
The manufacturer contacts CNC Onsite to discuss specifications for the monopile flanges. Our technical sales team will analyse the project and customer schedule. We will issue the quote based on the customers need and timeline. The customer issues the purchasing order.
02
Planning
We plan the technical part of the project, which includes preparation and programming of Goliath, the precision machine that will perform the milling. We plan staff availability and timing, including flexibility to accommodate potential changes to the schedule.
03
Implementation
Our technicians will conduct the precision milling of the flanges at the customer’s factory. Alternatively, CNC Onsite will train the customer’s own technicians for the operation of the machine. The team will use the Goliath machine to mill the flange faces, leaving them flat to within one millimeter.
04
Handover
After machining measurements are made, a measurement report is issued to the customer. Alternatively, the customer or a customer-contracted third party conduct the measurements. Once the measurement are complete, the customer signs off the work.
05
Follow-up
We offer follow-up meetings with the customer. CNC Onsite’s follow-up program is part of our high quality standards.
“Goliath, which can work both horizontally and vertically, can cope with features on large flanges such as double-tilted flanges and requirements for parallelism of the flange surfaces. Our Goliath machine can manage the many new complex flange designs, making it probably the most advanced and precise flange milling tool on the market”
Søren Kellenberger CEO, CNC Onsite
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