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Title: Non-Destructive Evaluation of Brine Tanks by Thermographic and Ultrasonic Methods
Contact: Lewis N. Lloyd
Project No.: 117955
Target Date: 01/31/2023
Abstract: VDOT controls approximately 400 above ground storage tanks for liquid deicing chemicals for its winter maintenance program. While these tanks are routinely inspected to identify signs of aging and damage, current methods may not adequately capture all defects, particularly if they are subsurface or too small to be seen during visual inspection. Therefore, to improve VDOT's ability to identify potential durability issues with these tanks , additional non-destructive evaluation methods need to be considered and assessed for applicability. This proposal seeks to use infrared thermography as a rapid method of inspecting large areas of the tank exterior followed by closer inspections with conventional and phased array ultrasonic methods of concerning areas identified with the former methods. Using IRT will save time and effort as it can quickly examine large areas simultaneously, since ultrasound alone will be too time- and labor-intensive to examine the entire structure. Therefore, the combined effort of both IRT and ultrasonic methods will ensure successful detection of defects.However, significantly more research is needed to answer a number of unknowns,including 1) use of passive vs. active thermography; 2) use of conventional and phased array ultrasound; 3) “threshold” measurements to indicate damage severity; 4) detection limits as a function of defect size and geometry,infrared image pixel size and camera settings, ultrasonic frequency, degree of deterioration, deterioration mechanism(s), etc.; 5) use of phased array ultrasound to “look behind” fittings and other protrusions; and 6) ease of use and applicability in the field. Upon successful completion of the research outlined in the proposal, the researchers will have produced a final research report that includes the data and findings along with guidelines for best practices and a technical brief with details and recommendations for VDOT’s field implementation, including testing frequency. 

     Alexander S. Brand
     Lewis N. Lloyd