Real Time & Long Term Acoustic Emission Monitoring: New ways to use Acoustic Emission - Application to Hydroelectric Penstocks and Paper Machine

For decades now, acoustic emission (AE) testing has been used in several fields of the industry, mainly for the control of pressure vessels, such as storage tanks, or reactors, or civil engineering structures, such as bridges. The specificity of acoustic emission technology is to be a global non-destructive method, able to detect and localize in real time active phenomenon, such as cracks, corrosion or leaks… In order to fully exploit the unique capabilities of this technique, we have implemented AE on new fields that need real time and long term monitoring. Two original cases are presented: The first one deals with strategic structure in the field of hydroelectric energy, i.e. the penstocks, that deliver water from a dam to hydraulic turbines. The challenge was to ensure the safety of an installation, built in the 50s, while continuing to produce electrical energy. Engineers have adapted existing technologies of acoustic emission to catch very specific degradation phenomena that could lead to the full rupture if not identified on time. The second case deals with the monitoring of rotating mechanical parts, such as bearings or gearboxes. We have implemented many monitoring techniques, including AE, on a large Paper Machine, in the frame of a European Project ‘SUPREME’ (SUstainable PREdictive Maintenance for manufacturing Equipment). We have found interesting correlations and complementarities between AE and many other physical parameters such as vibrations. The real time and continuous monitoring of five mechanical elements during six months, has allowed us to better understand the constraints linked to such complex environment and to draw conclusions on monitoring strategies. Today, based on significant feedback, CETIM may apply AE monitoring on a large field of cases.