Structural Health Monitoring of Above-Ground Storage Tank Floors by Ultrasonic Guided Wave Excitation on the Tank Wall

Abstract

There is an increasing interest in using ultrasonic guided waves to assess the structural degradation of above-ground storage tank floors. This is a non-invasive and economically viable means of assessing structural degradation. Above-ground storage tank floors are ageing assets which need to be inspected periodically to avoid structural failure. At present, normal-stress type transducers are bonded to the tank annular chime to generate a force field in the thickness direction of the floor and excite fundamental symmetric and asymmetric Lamb modes. However, the majority of above-ground storage tanks in use have no annular chime due to a simplified design and/or have a degraded chime due to corrosion. This means that transducers cannot be mounted on the chime to assess structural health according to the present technology, and the market share of structural health monitoring of above-ground storage tank floors using ultrasonic guided wave is thus limited. Therefore, the present study investigates the potential of using the tank wall to bond the transducer instead of the tank annular chime. Both normal and shear type transducers were investigated numerically, and results were validated using a 4.1 m diameter above-ground storage tank. The study results show shear mode type transducers bonded to the tank wall can be used to assess the structural health of the above-ground tank floors using an ultrasonic guided wave. It is also shown that for the cases studied there is a 7.4 dB signal-to-noise ratio improvement at 45 kHz for the guided wave excitation on the tank wall using shear mode transducers.

Structural Health Monitoring (SHM) and Determination of Surface Defects in Large Metallic Structures using Ultrasonic Guided Waves

“…The pitch-catch configuration is also known as through transmission. Because of the wide coverage capability of the pitch-catch method, it has been proposed by few researchers for inspecting the floor of fuel storage tanks, using lamb waves [ 62 , 63 ].…”

Monitoring of Critical Metallic Assets in Oil and Gas Industry Using Ultrasonic Guided Waves

“…The SH0 mode is an interesting alternative to the S0 mode for this application due to its non-dispersive characteristic [54]. Advances in flexible shear mode transducers led to a recent study [55] on their application to SHM of AST floors. This study evaluated the two modes of interest: S0 mode for normal excitation; and SH0 mode for shear excitations.…”

Experimental Study for Damage Identification of Storage Tanks by Adding Virtual Masses

“…At present, the detection methods applicable to monitoring of tanks mainly include X-ray detection [11], acoustic emission [12,13,14], ultrasonic detection [15,16,17,18], magnetic flux leakage detection [19,20], eddy current [21], etc. The advantage of these nondestructive detection methods [22] is that they do not depend on the finite element model [23] of the structure; however, they cannot quantitatively evaluate the degree of damage.…”