| Abstract [eng] |
Detecting and quantifying corrosion-type damage is vital for the petrochemical industry. To ensure a high level of safety and reliability, the storage tank and its floor should be periodically maintained in order to avoid corrosion-related accidents when hazardous chemical materials might get into the environment and groundwater. The main problem related to the inspection of the storage tanks and their floors, using conventional non-destructive testing methods is that, in most cases, the storage tank has to be emptied, cleaned and made safe for human entry before any inspection could be performed. Moreover, such operations are costly and time-consuming. Aim of the dissertation is to develop and investigate a method of measurement that enables to detect and measure corrosion-caused defects inside of an aboveground storage tank floor without emptying and cleaning the storage tank. Dissertation presented the regularities and parameters of the ultrasonic guided waves in the case of their propagation through shell-to-bottom and lap joint connections used in the construction of storage tank floor. Suggested the improved ultrasonic transmission tomography algorithm for the reconstruction of the true value of ultrasonic guided waves attenuation spatial distribution, that could be directly related to the general corrosion level, using optimisation for each projection. Obtained spatial sensitivity and resolution of ultrasonic transmission tomography determined by modelling and experiments. |
