According to a comprehensive study carried out by CCTechnologies in 1998, cost of corrosion to US economy was 3 % of the GDP in 1998 amounting to $276 Billions (FHWA-­‐ RD-­‐01-­‐156). From that amount, $121 billion was spent on corrosion control, from which $107 billion was spent on protective coatings. It was reported that better corrosion protection could save up 40% of that cost. Improved practices were sited as better coating quality control and effective inspection at time of coating application, routine/periodic coating inspection during the service life of the structure, and appropriate repair action when coating degradation, delaminate or substrate corrosion is detected In 2007, New York University Polytechnic Institute was awarded a grant by the gas industry to evaluate infrared thermography as a method for detection of early onset of corrosion in gas pipelines beneath the protective coating. Results indicated that it is possible to detect corrosion at stages earlier than it is possible to detect with current ultrasonic thickness gauges and it is possible to detect poor quality coating, such as the presence of air blisters, even in the absence of corrosion. Furthermore thermal imaging is a two dimensional technique and lend itself for inspection and documentation of surfaces.

The above study was the subject of my PhD dissertation. Now I would like to carryout a preliminary analysis of the application of infrared thermography as a tool for subsurface condition assessment of painted steel bridges. The objective is to detect early onset of corrosion and to detect paint delamination, both of which are not possible by visual inspection. Currently, federal guidelines hold the contractor responsible for the coating quality, however there is no practical methodology for evaluating the coating and subsurface condition.