Combining ultrasound non-destructive testing and bolting methods to improve reliability on bolted flange connections in offshore wind

摘要

This paper introduces the research undertaken to improve the reliability of bolted flange connections in structural engineering, with offshore wind turbines being used as an example. The current problem is that bolts are often over- or under-loaded, leading to premature failure. This shows that the existing loading methods cannot be relied on to balance the strains, which is the root cause of the bolting problem. This work highlights the importance of good asset management of bolted flange connections in the safety aspects of bolted flange connections. The purpose of this paper is to provide the basis of a new bolt loading process that consists of advanced coupling methods supported by non-destructive ultrasonic testing. In addition, this paper presents a comparison of the new method with the traditional torque tightening technique, supported by real project data. The results suggest that the new bolting process controls the individual bolt strains more effectively, and that non-destructive testing with ultrasound is key to help with quality assurance and asset management. It is anticipated that this will reduce long-term asset management risks associated with critical bolted flange joints that are used in wind turbine towers. It may have applications in other cases. According to the laboratory results, it was concluded that the combination of non-destructive testing with the tightening process provides a more reliable bolting method. This was later confirmed in the field using regular employees, the reliability of the new method has been confirmed by statistical analysis of 10,000 project data points. This paper contributes to non-destructive monitoring theory by confirming the importance of using modern NDT techniques and statistical analysis combined with mechanical processes to safely and reliably torque bolted flanges. The new method can increase the strain balance and improve the safety and reliability of bolted flange connections, and thereby improve long-term asset management.