The Enhancement of NDT Techniques through Active Thermal Infrared Thermography to Identify Corrosion under Insulation (CUI) in Downstream Piping

In the effort of sustaining the reliability of equipments, periodic maintenance and inspection is required. This is done by applying the non-destructive testing (NDT) techniques like ultrasonic, radiography, and etc. NDT act as the appropriate tool for engineers and inspectors to examine the presence and absence of any failures or defects on certain equipments without producing any disturbance to the equipments‟ process and operation [1]. In oil and gas industry, corrosion under insulation (CUI) is considered as the major problem arise today as it requires billion costs to inspect the corrosion involving the procedure to unwrap the insulation which will lead to 3 - 4 days operation. With the conventional NDT practice, this matter has been identified as time-consuming and costly operation. Therefore, the aim of this study was to validate the use of infrared thermography as NDT and E in locating and detecting CUI through lockin thermography testing. For this experimental study, a laboratory cell was designed to simulate the condition of CUI using the carbon steel plate (testing object) as a mock-up downstream pipe section. Factors include insulation thickness, defect‟s size, defect‟s depth, and the objective distance are the parameters affecting the accuracy of the results. For this purpose, infrared image correlation and numerical computation was used to predict the presence tendency of CUI. By numerical computation, it was demonstrated in this study that defect exhibit different temperature distribution as time elapsed. In contrast, temperature drops as the insulation becomes thick. By correlation, classification on thermal infrared colors governs the area of both defects and non-defects distinctively. It is obvious that the applicability of the present NDT and E to detect CUI depends on a heating condition and a relative difference of thermophysical property between the defect and its surrounding.