Some offshore wind turbine support structures may not meet their intended fatigue life expectations, according to a new case study released by Lloyd’s Register on Thursday, raising questions about long-term durability and inspection strategies in the sector.
The assessment, based on a North Atlantic wind farm comprising 60–70 turbines with a total capacity of 500–600 megawatts (MW), found that a critical joint in the jacket foundations could fail after 52 years — short of the expected 75-year fatigue design life.
Offshore wind turbines are typically designed for a 25-year operational lifespan using a fatigue design factor of three. Instead of recommending a redesign of the joint, Lloyd’s Register applied a reliability-based inspection strategy that uses stress-cycle modelling and fracture mechanics to predict failure probabilities and inform maintenance planning.
“Our findings show that using reliability-based methods allows operators to focus inspections where the risks are greatest,” said Kourosh Parsa, global head of technology – offshore and subsea at Lloyd’s Register. “By integrating sophisticated models and real-world inspection data, we can extend asset life, reduce costs and, most importantly, maintain safety.”
The study suggested initiating the first inspection by year nine, with future intervals dynamically adjusted based on observed conditions and data inputs. The methodology integrates Probability of Detection (PoD) curves to reflect evolving reliability estimates over time.
Traditional visual and ultrasonic inspections were found to be less effective for fatigue-critical components, prompting a recommendation for more advanced techniques such as Eddy Current and Alternating Current Field Measurement (ACFM), which may enable extended inspection intervals without compromising safety margins.
We’re enabling developers and operators to make better-informed decisions that optimise asset life and performance,” said Manuel Ruiz, head of offshore renewable solutions at Lloyd’s Register. “This proactive, risk-based approach is exactly how we support our clients in navigating complexity, controlling costs, and ensuring the long-term viability of their offshore wind investments.
Lloyd’s Register called for broader industry collaboration to improve inspection standards and share monitoring data. It also noted that further research is underway to enhance model accuracy and address challenges in reliability updating, including better calibration of crack growth parameters.
