Danish-designed inspection tool for wind turbine bolts cuts tensioning maintenance time in half The

ÅRHUS, Denmark - Aug. 27, 2021 - PRLog -- A necessary but time-consuming task performed by wind turbine technicians is to check for any loss of tension in the thousands of bolts holding the structures together. Using conventional methods, each bolt must be retensioned individually, a tedious exercise often taking days; but now, with "Bolt-Check" developed by Danish tools expert R&D, the bolt tension can be checked faster with higher accuracy and full traceability. This results in a time saving of up to 50 percent.Technicians also benefit ergonomically thanks to the reduction in the repetitive actions involved when continually handling heavy tightening tools.

Incorrect bolt tension in wind turbines is a common complication that can both result in expensive call-out charges and downtime. Checking the condition of the bolts to ensure safe and reliable performance is a key maintenance task.

Each manufacturer provides service instructions as to when preventative maintenance is due. This work can be time consuming and cumbersome as the tightening tools are often large and heavy. Furthermore, subsequent wear and tear resulting from re-tightening can be significant.

Capable of checking more than 100 bolts per hour, the Bolt-Check tool is light and hand-held and maintenance costs are reduced as only the ultrasonic sensor head gets worn over time.

Competitively priced with traceability feature

Unlike other sensor-based tools, Bolt-Check does not require specially manufactured bolt. Bolt-Check can be implemented at a cost of 3-4 euros per bolt. This compares to specialized bolts costing 10 times that. A unique traceability tag is added to each bolt in the Bolt-Check system for a detailed documentation trail.

Accuracy

Accurate to better than 5 percent, the tool offers an advantage compared to traditional torque-and-tension methods, for which the error tolerance can be as much as 30 percent.

Service technicians benefit and human errors reduced

Bolt-Check offers the simplicity of the "ping" test while using ultrasound to obtain a highly accurate result. Because Bolt-Check documents measurements electronically, potential human errors are reduced.

Patent

This patented approach gives bolt tension results to the necessary level of accuracy required. The patent makes use of the fact that the speed of sound in a bolt under tension is slower than an unloaded bolt, meaning the measured distance is longer than it should be. For a given, calibrated batch of bolts, the difference between the ultrasonic and mechanically measured distances is directly related to the tension in the bolt. This enables accurate tension measurement without having to loosen each bolt first.

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