Session: Virtual Presentations in Acoustics, Vibration, and Phononics

Paper Number: 96869

96869 - Research on the Attenuation Characteristics of Acoustic Emission From Corrosion of Tank Bottom Plate 

Atmospheric storage tanks are important storage and transportation equipment in petrochemical industry. The failure of them often lead to serious accidents and environmental pollution. It has been reported that tank floor corrosion is the main cause of failure of steel storage tanks, so it is important to detect and evaluate the corrosion state of the tank floor. 

Acoustic emission is a nondestructive method that refers to the elastic waves generated by the release of energy due to microstructure changes of materials. As an internationally recognized online detection method of tank floor corrosion, it has been widely used to monitor atmospheric tanks. However, with the increase of the storage tank, acoustic emission is faced with the problem of missing detection just due to the attenuation of AE signals during propagation process. In order to avoid missing detection, the propagation path and the attenuation characteristics of AE signal from the tank floor corrosion are investigated.

 AE attenuation tests are conducted on a storage tank with dimensions of φ 15m×3m when the medium are atmosphere and water, respectively. Lead break signal is selected to simulate corrosion acoustic emission source. AMSY-6 AE system (Vallen, Germany) together with VS30 sensors are used to detect AE signals. The built-in pre amplifier of the sensor is 46dB. The AE sensors are mounted on the tank wall 50 away from the tank floor by magnetic holding device. The lead break is performed on the tank floor along the warp of the tank floor as well as the tank wall. The AE signals from the lead break are collected and analyzed.

First the effect of the interface of the tank floor and cap is studied by comparing the AE attenuation curves of the tank floor and tank wall obtained when the tank is empty. The AE attenuation of the tank floor is obviously larger than that of the tank wall. Combined with the finite element simulation result, this is because the cap of the tank can absorb the energy of AE signals. Therefore, it is not scientific to use the attenuation of tank wall to predict that of tank floor.  

Then, the propagation path together with the effect of medium on the attenuation of AE signals is investigated when the tank is full of water. It is found the AE signals propagate along both tank floor and water. The amplitude of AE signals along the tank floor is not linearly attenuated with the increase of propagation distance, but increases greatly due to the influence of circular boundary in the last half of the bottom plate of storage tank, and a maximum appears. The amplitude of AE signals along the water attenuates linearly. The amplitude of AE signals along the tank floor and the water is determined by the location of AE sources.

Presenting Author: Yongna Shen China special equipment inspection and research institute,Key Laboratory of Nondestructive Testing and Evaluation for State Market Regulation

Presenting Author Biography: Yongna Shen, doctor of engineering, engaged in acoustic emission technology and magneto acoustic emission

Authors:

Yongna Shen China special equipment inspection and research institute,Key Laboratory of Nondestructive Testing and Evaluation for State Market Regulation
Gongtian Shen China special equipment inspection and research institute
Pengcheng Gan China special equipment inspection and research institute
Junjiao Zhang China special equipment inspection and research institute,Key Laboratory of Nondestructive Testing and Evaluation for State Market Regulation
Yilin Yuan China special equipment inspection and research institute,Key Laboratory of Nondestructive Testing and Evaluation for State Market Regulation