Active damage detection of LNG tank under different static pressure using piezoelectric sensors

Liquefied natural gas (LNG) tanks are a kind of large-scale equipment used to transfer LNG from storage worldwide. Due to the high pressure, different degrees of damage or leakage can occur on the tank’s surface, resulting in both economic loss and harmful disasters to the surrounding environment and people. Therefore, it is imperative to monitor the health condition of the tank continuously. In this paper, a piezoelectric sensor-based active monitoring system was used to monitor the damage to the tank. The mechanical behaviour of the LNG Type-C tank was analyzed under different static pressure stresses by finite element software to identify the damage location. Different lengthening cracks had been induced on the tank due to FE analysis results. In the experimental portion, two PZT patches were attached as sensors and actuators to the tank’s surface at the same distance, and an active monitoring system was used to identify the different damage conditions. Wavelet packet-based analysis was performed to note the attenuation of the energy index when the signals pass through the crack. The results show that the signal changes its characteristics when a crack appears on the tank surfaces.