Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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Technology for the Detection of Corrosion Defects in Buried Pipes of Nuclear Power Plants with 3D FEM

3D 유한요소법을 이용한 원전 매설배관 부식결함 탐상기술 개발

  • Kim, Jae-Won (Power Engineering Research Institute, KEPCO Engineering & Construction Company) ;
  • Lim, Bu-Taek (Materials Engineering Department, KEPCO Engineering & Construction Company) ;
  • Park, Heung-Bae (Power Engineering Research Institute, KEPCO Engineering & Construction Company) ;
  • Chang, Hyun-Young (Power Engineering Research Institute, KEPCO Engineering & Construction Company)
  • 김재원 (KEPCO E&C, 미래기술연구소) ;
  • 임부택 (KEPCO E&C, 재료기술그룹) ;
  • 박흥배 (KEPCO E&C, 미래기술연구소) ;
  • 장현영 (KEPCO E&C, 미래기술연구소)
  • Received : 2018.12.04
  • Accepted : 2018.12.13
  • Published : 2018.12.31
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Abstract

The modeling of 3D finite elements based on CAD data has been used to detect sites of corrosion defects in buried pipes. The results generated sophisticated profiles of electrolytic potential and vectors of current distributions on the earth surface. To identify the location of defects in buried pipes, the current distribution on the earth surface was projected to a plane of incidence that was identical to the pipe locations. The locations of minimum electrolytic potential value were found. The results show adequate match between the locations of real and expected defects based on modeling. In addition, the defect size can be calculated by integrating the current density curve. The results show that the defect sizes were $0.74m^2$ and $0.69m^2$, respectively. This technology may represent a breakthrough in the detection of indirect damage in various cases involving multiple defects in size and shape, complex/cross pipe systems, multiple anodes and stray current.

Keywords

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Fig. 1 Example of test APEC indications on buried pipes of from brochure of Structural Integrity Associate, Inc. [4].

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Fig. 2 Geometric model of an anode and pipes.

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Fig. 3 Mesh generation of an anode and pipes.

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Fig. 4 Electrolytic potential distribution on buried pipes (applied current: 0.025 A).

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Fig. 5 Electrolytic potential distribution on earth surface; (a) 3D plot, (b) 2D plot.

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Fig. 6 Geometric design for detecting defect locations on buried pipes.

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Fig. 7 Electrolytic potential distribution on earth surface and plane of incidence.

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Fig. 8 Electrolytic potential distribution on a plane of incidence; (a) 2D plot, (b) 1D plot.

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Fig. 9 Geometric realization for defect locations comparison and defects size calculation.

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Fig. 10 Comparison between locations of a real defect and expected defect after modeling; (a) Electrolytic potential of earth surface and buried pipes, (b) Comparison of defect locations (right), (c) Comparison of defect locations (left).

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Fig. 11 Current density curve on buried pipe with defects.

Table 1 Governing equation of the secondary current distribution

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Table 2 Parameters for simulation runs

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References

  1. EPRI 1016456, Recommendations for an Program to Control the Degradation of Buried and Underground Piping and Tanks, Revision 1 (2010).
  2. KISTEK, Development of corrosion environment survey and analysis method for buried pipe II (1999).
  3. KOGAS, Protection technique handbook, p. 18 (2003).
  4. EPRI 1022962, Plant Engineering: Evaluation of Indirect Assessment Techniques for Coating Flaw Detection (2011).
  5. H. Y. Chang, H. B. Park, K. T. Kim, Y. S. Kim, and Y. Y. Jang, KPVP, 11, 61 (2015).
  6. H. Y. Chang, K. T. Kim, B. T. Lim, K. S. Kim, J. W. Kim, H. B. Park, and Y. S. Kim, Corros. Sci. Tech., 16, 115 (2017).
  7. Elizabeth Nicholson, B.Eng., Coatings and Cathodic Protection, http://www.cath-tech.com (2012).
  8. COMSOLTM, Guidebook of COMSOLTM Multiphysics (Chemistry-Electrochemistry), p. 174, ALTSOFT (2014).