T-joints are essential components in the construction of offshore wind towers, where critical welds hold together sections of the tower. The quality of these welds directly impacts the overall strength and durability of the structure. However, inspecting T-joints is notoriously challenging due to their complex geometries and the difficulty of accessing certain areas.
Eddyfi Technologies' PAUT solutions are specifically designed to address these challenges. With advanced imaging capabilities, PAUT provides precise, high-resolution scans that can reveal flaws or weaknesses in T-joint welds that might otherwise go unnoticed. The ability to perform these inspections with such accuracy is crucial for ensuring the long-term reliability of offshore wind towers.
Here, the Total Focusing Method (TFM) remote scan has proven to be the most effective inspection technique, primarily for safety reasons and also because of the wide scan width required for the scan path and coupling control. Typical scan lengths of the T-joint sections are around 5 meters (16 feet), both when testing from the top side and the bottom side. The 64-element, 5 MHz probe is fixed in a probe holder for direct coupling via a 3mm (0.1in) water gap and has a cable length of 30m (98ft). The remote-controlled scanner moves the probe, allowing additional transverse shifts for correctly guiding the probe along the scan path. The scanning speed is 17mm or 0.7in/s (~1m or 3ft/minute), providing a scan resolution of 1mm (0.04in), and four video cameras are used to control the test procedure.
T-joint weld inspection on an offshore wind turbine tower
The blade root is one of the most critical areas of a wind turbine, where the blade connects to the hub. This connection must withstand immense forces, and any defect or crack in this area can lead to catastrophic failure. Traditional inspection methods often struggle to detect flaws deep within the blade root due to its complex geometry.
Eddyfi Technologies addresses this challenge with the half-skip TFM, a revolutionary approach that provides high-resolution imaging capable of detecting even the smallest flaws in the blade root. By utilizing half-skip TFM, inspectors can effectively "see" inside the complex structure, ensuring that potential issues are identified and addressed before they escalate into significant problems.
The following image demonstrates TFM and the superimposition of a CAD file to ease the inspection diagnostic. The inspection was carried using a 5 MHz probe of 64 elements, a pitch of 0.6mm (0.02in), and a wedge of 55° shear waves.
TFM data superimposed on CAD file for contextual results
The benefits of using half-skip TFM for blade root inspections are clear: enhanced accuracy, reduced inspection time, and improved safety. These advantages make it an indispensable tool for maintaining the structural integrity of offshore wind turbines.
To learn more about TFM, the ultrasonic array technique used to synthetically focus at every point of a region of interest, visit here.
When the inspection job calls for mapping extensive composite components, who wouldn’t accept a helping hand? Or in this case, a 3-axis rotating arm… Composite material evaluation usually consists of assessing large structures like wind turbine blades. Considering their critical functions, it’s important to ensure their structural integrity. Non-Destructive Testing (NDT) is used for detecting defects at both the manufacturing stage and while the assets are in service. Regular inspection enables engineers to determine remaining useful life and proactively plan any maintenance or repair work required.
The Gekko® was the first portable PAUT unit to offer standard support for 3-axis encoding, making it possible to use paintbrush-like scanners for fast screening of large plates; there is no need to create raster scans. Just like painting a picture, a wheel probe can be used to acquire data along a line.
The Gekko supports a 3-axis encoder for TFM with a PAUT scanner
The scanner pictured above features both a rotational arm and head, using three encoders to perform 3D ultrasonic mapping with PAUT or TFM probes. It affixes by vacuum (with magnets an option for ferrous surface inspection applications). Why use TFM over PAUT? Like the name indicates, the Total Focusing Method offers a high resolution visual of an entire region of interest versus an image generated with PAUT generally only focused in the focal area of the beam. Depending on your application, either ultrasonic method may be the ideal technique for highly accurate and ergonomic 3D mapping of composite parts like wind turbines.
See the Gekko performing a 3-axis inspection in the video below. The zone is completely covered using this method, and inspectors will appreciate the auto-stitching and positioning making for easier assessment.
Gekko is the field proven TFM solution for composite inspection and so much more. If you need repeatable, actionable, meaningful and preventative data collection results, contact us for the perfect solution.
From beginning to end, the VersaTrax™ M-Series miniature magnetic crawler is a proven constant that can be found performing internal and external remote visual inspection (RVI) of wind turbine towers and blades worldwide. The versatile inspection robot features a 360° continuous tilt camera that can operate in air and underwater in otherwise inaccessible industrial environments. Delivering 1080p resolution real-time video footage, the VersaTrax operates on a user-friendly software platform leveraging the variable intensity spot and flood lights and parallel laser lines to collect the precise data required for a comprehensive, comparable inspection report. Moreover, the robotic platform can accommodate PAUT sensors for more detailed information. Learn more here.
Eddyfi Technologies' comprehensive PAUT solutions, including half-skip TFM, advanced TFM imaging and remote deployment, are essential tools for ensuring the safety, efficiency, and reliability of offshore wind tower inspections. As the offshore wind industry continues to expand, the need for precise, reliable inspection methods will only grow. Eddyfi Technologies is at the forefront of this effort, providing the advanced solutions necessary to meet these challenges head-on.
For more information on how Eddyfi Technologies' PAUT solutions can benefit your offshore wind inspection needs, contact us today or explore our full range of solutions to find the right fit for your project.
Ready to equip your team with the best tools in the industry? Procure PAUT probes at the Eddyfi eStore and experience the precision and reliability that Eddyfi Technologies is known for.