초음파 적외선 열화상 기법을 적용한 탄소강관 용접부 결함 검출에 관한 건전성 평가

Abstract

The piping system accounts for a large part of the machinery structure of the plant, and is considered as a very important mechanical structure for the plant safety. Accordingly, it is used in most energy plants in the nuclear, gas and heavy chemical industry. In particular, the piping system of the nuclear plant is generally configured in a complicated form for generation using the reactor and its cooling. The piping equipment is exposed to diverse loads such as the weight, temperature, pressure and seismic load from pipes and fluids, and is used to transfer steam, oil and gas. The infrared thermography technique is increasingly used in medical, generation, electric power, aviation and composite material sectors. It will be applied in more areas because it can obtain visual images in real time about the defects in a larger area than that of the existing non-destructive test. In the ultrasonic infrared thermography, which is an active thermographic technology, the 15-100 kHz ultrasonic wave is applied to the subject, and the resulting heat from the defective parts is measured using an thermographic camera. Because this technique can inspect a large area simultaneously and detect the defects such as cracks and delaminations in real time, it is used for detecting the defects in the new and renewable energy, car and aerospace industries, and recently, in the piping defect detection. In this study, the ultrasonic infrared thermography technique was used to detect the information for the diagnosis of the nuclear equipment and structure. Test specimens were prepared with the piping materials for nuclear plants, and the optimally designed ultrasonic horn and ultrasonic vibration system was used to determine damages on the nuclear plant pipings and detect the defects. In addition, the detected images were used to improve the reliability of the surface and internal defect detection for nuclear piping materials and their field applicability and reliability was verified.