Loss of clamp load and fatigue are common failure modes for bolted joints subject to dynamic loads. These conditions are the result of insufficient bolt tension during installation tightening, as well as the inaccuracy of typical torque/tension methods used to complete periodic in-service fastener checks. Critical bolted joints on wind turbines—such as tower, bearing, hub, and blade connections—are subjected to complex cyclic loads throughout their 20-year life.
By insuring fastener tension is maintained within +/-5 percent of design specification, RotaBolt® load-monitoring fasteners assure equipment reliability and safety while providing increased operation uptime and reduced maintenance cost benefits over the life of wind turbine bolted joints.
EGC Enterprises, Inc., manufacturer of RotaBolt fasteners for North America, has published a study covering bolted joint tightening and maintenance for wind turbines. The study illustrates the cost and time savings benefits, as well as operating efficiency improvements achieved via use of RotaBolts. The time and cost required to complete typical slew-ring bearing bolt in-service checks using standard torque/tension maintenance checks (+/-30 percent accurate) are compared to RotaBolt fingertip load monitor in-service checks (+/-5 percent accurate).
It is clearly shown that by introduction of RotaBolts as standard hardware for important and frequently maintained wind turbine connections, the results are increased operating uptime and greatly reduced time to perform in-service fastener tension checks. RotaBolts allow 100 percent tension verification in less time than it takes to complete a typical 10 percent torque check of standard fasteners. To request a copy of the study contact Brian Newcomb at (800) 342-0211 or