Some offshore wind turbine support structures may fall short of required fatigue life expectations, according to a new report from Lloyd’s Register.
The case study assessed a North Atlantic wind farm of 60–70 turbines totalling 500–600MW and found that a critical jacket foundation joint would fail to meet the expected 75-year fatigue design life, reaching its limit after just 52 years.
Offshore turbines are typically designed for 25 years using a fatigue design factor of three.
Instead of redesigning the joint, the study applied a reliability-based inspection approach using stress-cycle and crack-growth models to predict failure probability and guide risk-based maintenance.
This method combines S-N modelling with fracture mechanics analysis and integrates inspection results using Probability of Detection curves to dynamically update schedules based on real-world data.
Lloyd’s Register said the analysis suggested the first inspection should be carried out by year nine, with intervals adjusted according to the method and findings.
However, it warned that visual and ultrasonic techniques were less effective for fatigue-critical components, recommending more advanced methods such as Eddy Current or ACFM, which may permit longer intervals with adjusted safety margins.
Kourosh Parsa, global head of technology – offshore and subsea at LR, said: “Our findings show that using reliability-based methods allows operators to focus inspections where the risks are greatest.
“By integrating sophisticated models and real-world inspection data, we can extend asset life, reduce costs and, most importantly, maintain safety.”
Manuel Ruiz, head of offshore renewable solutions at LR, said: “We’re enabling developers and operators to make better-informed decisions that optimise asset life and performance.
“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 greater collaboration across the industry to refine inspection standards, share real-time monitoring data and adopt more flexible definitions of acceptable reliability.
The company said further research is underway to improve model precision and address practical challenges in applying reliability updating, including better calibration of crack growth parameters.