Abstract
This paper is concerned with an application of the infrared thermographic technique for detection of back-side corrosion type flaws in bottom floor of oil storage tanks. For detection of back-side flaws, we employ the active method, in which the surface-coated steel plates with various sizes of corrosion type flaws will be heated over coatings with an external thermal stimulation and afterwards the infrared scanning camera will be activated and then their thermal responses will be recorded. The two-dimensional thermal images due to the back-side flaws were measured for different thicknesses of coating. The digital data on temperature distributions after the image processings were analysis for sizing the back-side flaws, and comparisons between temperature distribution changes and flaw sizes were made. As the result, it is found that the thermal image shape and temperature distribution changes are correlated the shape and depth of back-side flaws respectively. The quantitative method for determining flaw diameter and depth are also presented. The results obtained in this paper fulfills the expectations for capabilities of the thermographic to be used in actual oil storage tank floor inspection.
