Presentation of an Innovative Method Based on Ultrasonic Waves Propagation: Monitoring of Bolt Tightening Efforts on Nuclear Equipment

The monitoring of tightening efforts on bolted joints with the existing means is tedious and its accuracy is difficult to control (torque wrench, dial gauge, hydraulic tightening). Knowing the accurate bolt tightening stresses becomes essential in sensitive areas such as nuclear, petrochemistry, military and maritime sectors. It is in this context that Apave Company proposes a suitable approach for the monitoring of tightening efforts by means of ultrasonic waves. This approach has proven its worth since 2013 by solving many industrial issues of Apave partners in nuclear field and heavy mechanics. The monitoring method is based on the accurate analysis of the time of flight of ultrasonic waves. It leads to the knowledge of the stress value in each bolt, with high accuracy compared to the existing tightening means.