Structural Health Monitoring of Industrial Piping Systems Based on Guided Elastic Waves

In the framework of the EU project SAFE PIPES (Safety Assessment and Lifetime Management of Industrial Piping Systems) elastic waves in the frequency range between 70 and 350 kHz, generated and detected by appropriate transducer arrays, are used to monitor the structural integrity of pipes by comparing their actual state with a predefined reference state. For these purposes, theoretical, numerical, and experimental results are combined to study guided wave propagation and wave interaction with relevant defects in detail. Based on these findings, a guided wave based multi-channel structural health monitoring (SHM) system is designed and applied to identify and monitor structural defects in steel pipes and a titanium elbow. The potential use of synthetic aperture techniques is discussed yielding spatial distributions of damage parameters along the pipe. The results reveal that guided wave based SHM in the kHz frequency regime has great potential for online monitoring of piping systems. It combines imaging techniques with long range detection capabilities and therefore closes the gap between local high-frequency NDE on the one hand and global low-frequency vibration analysis on the other hand.