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Evaluation of Improvement of Detection Capability of Infrared Thermography Tests for Wall-Thinning Defects in Piping Components by Applying Lock-in Mode

적외선열화상 시험에서 위상잠금모드 적용에 따른 배관 감육결함 검출능력 개선 평가

  • 김진원 (조선대학교 원자력공학과) ;
  • 윤경원 (조선대학교 기계설계공학과)
  • Received : 2013.03.07
  • Accepted : 2013.06.10
  • Published : 2013.09.01

Abstract

The lock-in mode infrared thermography (IRT) technique has been developed to improve the detection capability of defects in materials with high thermal conductivity, and it has been shown to provide better detection capability than conventional active IRT. Therefore, to investigate the application of this technique to nuclear piping components, lock-in mode IRT tests were conducted on pipe specimens containing simulated wall-thinning defects. Phase images of the wall-thinning defects were obtained from the tests, and they were compared with thermal images obtained from conventional active IRT tests. It showed that the ability to size the detected wall-thinning defects in piping components was improved by using lock-in mode IRT. The improvement was especially apparent when detecting short and narrow defects and defects with slanted edges. However, the detection capability for shallow wall-thinning defects did not improve much when using lock-in mode IRT.

위상잠금모드가 적용된 적외선열화상 시험법은 열전도도가 큰 재료에서 결함의 검출능력을 향상시키기 위해 개발되었으며, 기존의 적외선열화상 기법에 비해 우수한 결함 검출능력을 보이는 것으로 알려져 있다. 따라서, 본 연구에서는 원전 배관 감육결함 검출에서 위상잠금모드 기법의 적용 효과를 살펴보기 위해서, 감육결함이 가공된 배관 시편을 대상으로 위상잠금모드를 적용하여 적외선열화상 시험을 수행하였다. 시험 결과로부터 감육결함에 대한 위상이미지를 얻고, 이것을 기존의 적외선열화상시험법으로 구한 열화상이미지와 비교하였다. 비교 결과, 위상잠금모드의 적용이 감육결함에 대한 형상 결정 능력을 향상시키는 것을 확인하였다. 이러한 개선 효과는 폭과 길이가 작거나 경계가 경사진 감육결함에서 뚜렷하였다. 그러나, 깊이가 얕은 감육결함의 검출능력은 크게 향상되지 않았다.

Keywords

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