적외선 열화상 기술을 이용한 배관의 최적 시험조건 결정에 관한 연구

Abstract

Non-destructive testing (NDT) method with the merits of rapid response, economic efficiency, and manifold applications has been an important role in industries from the safety diagnosis of large infra structure to the reliability evaluation of small products. There are many efficient NDT methods such as visual testing(VT), radio-graphic testing(RT), ultrasonic testing(UT), magnetic testing(MT), liquid penetrant testing(LT), eddy current testing (ET), acoustic emission(AE), thermography. Generally, VT, PT, MT, and ET are applied for the detection of surface defects and UT and RT are done for internal defects. NDT methods based on optical metrology such as Thermography, Holography, Electronic Speckle Pattern Interferometry, Shearography etc can provide solution to the problems of previous methods. Infrared thermography application techniques is a two-dimensional non-contact nondestructive evaluation (NDE) that can detect internal defects from the thermal distribution by the inspection of infrared light form the object surface. Infrared thermal imaging of bulk is different form that of a defect, In a heated metal with a internal defect, and then location and size of a defect can be measured by the analysis of thermal imaging pattern. This study conducted Pulsed Infrared Thermography and Lock-in infrared Thermography test for Pipe specimen of two type(4inch, 2.5inch) artificial wall Thinning defect to find an optimal condition for IRT for Wall Thinned Piping components. Pulsed infrared thermal imaging is a method to inspect a defect by in directly heating treatment, and lock-in infrared thermal imaging is a method to detect a defect by directly heating treatment, respectively. In the experiment two Halogen Lamps, whose full power capacity are 1 kW, were used to heat specimens, and the exposure distance between specimen and Lamp and the Lamp power were considered as experimental parameters. when the exposure distance is 1m,2m,3m and the exposure rate is higher than 60% of full power. In the case of 4inch, Infrared and Lock-in thermal Image of wall-thinning defect was clearer under the conditions of higher exposure rate and exposure distance of 2m than under the conditions of lower exposure rate and exposure distance of 1m and 3m. but Image of 2.5inch wall-thinning defect was clearer under the conditions of higher exposure rate and exposure distance of 1m than under the conditions of lower exposure rate and exposure distance of 2m. Also, it was recognized that the detectability of Defect is similar for both Pulsed Infrared thermography and Lock-in thermography.