Non-contact ultrasonic detection method for storage tank floor corrosion based on dynamic wavelet fingerprint technology

Abstract

The invention relates to a storage tank bottom plate corrosion noncontact ultrasonic detection method based on a dynamic wavelet fingerprint technology. The method is characterized by comprising the following steps: selecting a steel plate which is smaller than a water trough from a detected test piece; immersing the detected steel plate into the transparent glass water trough, and fixing an immersion-type non-focusing probe on a movable arm of a four-axis linkage scanning platform; determining a scanning step in an X direction and a Y direction; analyzing a group of acquired echo signals by virtue of a computer, and drawing an original time domain chart of waveforms of the echo signals; intercepting a section of the time domain chart as an effective detection zone; resolving an intercepted time domain signal by utilizing wavelet transformation of the dynamic wavelet fingerprint technology; conducting continuous wavelet transformation on a signal after denoising treatment to obtain a wavelet coefficient matrix; conducting normalization processing on the acquired matrix; simultaneously writing an acquired imaging time point and a location coordinate of the time point recorded during the scanning into the matrix to obtain a C scanning image. According to the method, corrosion defects on a storage tank bottom plate can be detected under the situation that a storage tank does not need to be cleaned, so that the detection efficiency can be improved, and the detection cost can be reduced.

Description

technical field [0001] The invention relates to a non-contact ultrasonic detection method for plate structure corrosion defects, in particular to an ultrasonic scanning imaging method for storage tank bottom plate corrosion based on dynamic wavelet fingerprint technology. The method is applicable to the detection of corrosion defects on bottom plates of atmospheric vessels and large storage tanks, and belongs to the field of nondestructive testing. Background technique [0002] As a special equipment for storing crude oil, chemical raw materials and their products, large atmospheric storage tanks are widely used in many fields such as petroleum, chemical industry, national defense, transportation and so on. Because it contains flammable, explosive, highly toxic or corrosive liquids, and operates in a high temperature and high pressure environment for a long time, the bottom plate of the storage tank is prone to corrosion defects. The corrosion state of the storage tank bott...

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Problems solved by technology

Although these methods can avoid some leakage accidents caused by corrosion, but due to the need to stop production for detection, the detection time is long, the cost is high, and the determination of the maintenance object is blind, which is easy to cause missed detection and over-inspection, which affects the safe and economical operation of the storage tank. bring hidden danger

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