Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
권호 표지
DOI QR코드

DOI QR Code

Investigation of Pitting Corrosion of Copper Heat-Return Pipe in District Heating

지역난방 구리난방환수관의 공식 원인 분석

  • Keun Hyung Lee (Department of Materials Science and Engineering, Chungnam National University) ;
  • Min Ji Song (Department of Materials Science and Engineering, Chungnam National University) ;
  • Tae Uk Kang (Department of Materials Science and Engineering, Chungnam National University) ;
  • Woo Cheol Kim (Plant management & QC division, Korea District Heating Corporation) ;
  • Heesan Kim (Department of Nanomaterials Engineering, Hongik University) ;
  • Soo Yeol Lee (Department of Materials Science and Engineering, Chungnam National University)
  • 이근형 (충남대학교 신소재공학과) ;
  • 송민지 (충남대학교 신소재공학과) ;
  • 강태욱 (충남대학교 신소재공학과) ;
  • 김우철 (한국지역난방공사 플랜트기술처 플랜트관리 QC부) ;
  • 김희산 (홍익대학교 재료공학과) ;
  • 이수열 (충남대학교 신소재공학과)
  • Received : 2024.07.27
  • Accepted : 2024.08.02
  • Published : 2024.08.30
Download PDF
⟨ Previous Next ⟩

Abstract

This work examined pitting corrosion failure of a copper heat-return pipe used in a district heating system. The copper pipe was corroded with a 48% reduction in thickness due to localized corrosion on the inner surface exposed to heating water of 20 ~ 40 ℃. Fe and Si elements as corrosion products were found around pits. Cl element was also observed, which accelerated oxidation of copper inside pits. Cu2O deposits on the pit's bottom surface decreased the pH inside the pit. X-ray diffraction analysis revealed hematite, cuprite, malachite and brochantite as corrosion products. Chemical analysis demonstrated that Fe and Si elements did not exist in the copper, supply water, or heating water, indicating that Fe and Si species might have entered into the pipe from the exterior. These results indicated that pits were initiated due to ion concentration gradient near Fe and Si species. Moreover, the interior of pits had lower pH due to Cl- concentration and Cu2O reactions, which accelerated the pit's growth and led to formation of pinholes. Additionally, we confirmed that the type of pitting corrosion was a complex combination of types I and II based on the HCO3-/SO42- ratio, pH, temperature, and corrosion products.

Keywords

Acknowledgement

본 연구는 한국지역난방공사의 지원을 받아 연구를 수행하였습니다.

References

  1. E. S. M. Sherif, Corrosion behavior of copper in 0.50 M hydrochloric acid pickling solutions and its inhibition by 3-amino-1, 2, 4-triazole and 3-amino-5-mercapto-1, 2, 4-triazole, International journal of electrochemical science, 7, 1884 (2012). Doi: https://doi.org/10.1016/S1452-3981(23)13847-8 
  2. B. Duran, G. Bereket and M. Duran, Electrochemical synthesis and characterization of poly (m-phenylenediamine) films on copper for corrosion protection, Progress in Organic Coatings, 73, 162 (2012). Doi: https://doi.org/10.1016/j.porgcoat.2011.10.008 
  3. M. Rizvi, H. Gerengi, S. Kaya, I. Uygur, M. Yildiz, I. Sarioglu, Z. Cingiz, M. Mielniczek and B. E. Ibrahimi, Sodium nitrite as a corrosion inhibitor of copper in simulated cooling water, Scientific reports, 11, 8353 (2021). Doi: https://doi.org/10.1038/s41598-021-87858-9 
  4. J. B. Lee and H. S. Jung, Investigation on causes of pitting corrosion in sprinkler copper tubes, Corrosion Science and Technology, 13, 6 (2014). Doi: http://dx.doi.org/10.14773/cst.2014.13.1.6 
  5. S. H. Suh, Y. J. Suh, H. G. Yoon, J. H. Oh, Y. J. Kim, K. M. Jung and H. S. Kwon, Analysis of pitting corrosion failure of copper tubes in an apartment fire sprinkler system, Engineering Failure Analysis, 64, 111 (2016). Doi: https://doi.org/10.1016/j.engfailanal.2016.03.009 
  6. S. H. Suh, Y. J. Suh, J. H. Lee and H. S. Kwon, Inhibition of pitting corrosion failure of copper tubes in wet sprinkler systems, Corrosion Science and Technology, 19, 89 (2020). Doi: https://doi.org/10.14773/cst.2020.19.2.89 
  7. S. H. LEE, J. G. Kim and J. Y. Koo, Investigation of pitting corrosion of a copper tube in a heating system, Engineering Failure Analysis, 17, 1424 (2010). Doi: https://doi.org/10.1016/j.engfailanal.2010.05.002 
  8. T. Fujii, T. Kodama and H. Baba, The effect of water quality on pitting corrosion of copper tube in hot soft water, Corrosion Science, 24, 901 (1984). Doi: https://doi.org/10.1016/0010-938X(84)90127-6 
  9. J. Jonsson and R. J. Oliphant., Causes of copper corrosions plumbing systems, Foundation for water Research, Allen House, Marlow U. K. (2010). Doi: https://www.aquatherm.com.au/images/pdf/FWR_causes_of_copper_corrosion.pdf 
  10. M. K. Hong, H. B. Chae, W. C. Kim, J. G. Kim, H. S. Kim and S. Y. Lee, Failure analysis of a water wall boiler tube for power generation in a district heating system, Metals and Materials International, 25, 1191 (2019). Doi: https://doi.org/10.1007/s12540-019-00267-6 
  11. H. B. Chae, W. C. Kim, H. S. Kim, J. G. Kim, K. M Kim, and S. Y. Lee, Corrosion failure analysis of condensate pre-heater in heat recovery steam generator, Corrosion Science and Technology, 20, 69 (2021). Doi: https://doi.org/10.14773/cst.2021.20.2.69 
  12. M. K. Hong, H. B. Chae, Y. S. Kim, M. J. Song, J. M. Cho, W. C. Kim, T. B. Ha and S. Y. Lee, Flow-accelerated corrosion analysis for heat recovery steam generator in district heating system: Korean Journal of Materials Research, 29, 11 (2019). Doi: https://dx.doi.org/10.3740/MRSK.2019.29.1.11 
  13. Y. S. Kim, H. B. Chae, M. K. Hong, M. J. Song, J. M. Cho, W. C. Kim, T. B. Ha, and S. Y. Lee, Corrosion failure analysis of the convection part of district heating peak load boiler, Corrosion Science and Technology, 18, 55 (2019). Doi: https://doi.org/10.14773/cst.2019.18.2.55 
  14. J, M. Cho, H. B. Chae, H. S. Kim, J. G. Kim, W. C. Kim, J. C. Jeong and S. Y. Lee, Failure analysis of air vent connected with heat supply pipeline under manhole, Corrosion Science and Technology, 19, 196 (2020). Doi: https://doi.org/10.14773/cst.2020.19.4.196 
  15. H. J. Lee, H. B. Chae, J. M. Cho, W. C. Kim, J. C. Jeong, H. S. Kim, J. G. Kim, and S. Y. Lee, Corrosion failure analysis of air vents installed at heat transport pipe in district heating system, Corrosion Science and Technology, 19, 189 (2020). Doi: https://doi.org/10.14773/cst.2020.19.4.189 
  16. Y. S. Kim, H. B. Chae, W. C. Kim, J. C. Jeong , H. S. Kim , J. G. Kim and S. Y. Lee, Failure analysis on localized corrosion of heat transport pipe in district heating system, Corrosion Science and Technology, 19, 122 (2020). Doi: https://doi.org/10.14773/cst.2020.19.3.122 
  17. H. B. Chae, H. Wang, M. K. Hong, W. C. Kim, J. G. Kim, H. S. Kim and S. Y. Lee, Stress corrosion cracking of a copper pipe in a heating water supply system, Metals and Materials International, 26, 989 (2020). Doi: https://doi.org/10.1007/s12540-019-00386-0 
  18. E. Mattsson and A-M. Fredriksson, Pitting corrosion in copper tubes-cause of corrosion and counter-measures, British Corrosion Journal, 3.5, 246 (1968). Doi: https://doi.org/10.1179/000705968798326037 
  19. S. J. Yu, S. J. Park, H. K. Kim, K. H. Ahn, Y. H. Lee and C. S. Kim, Study of the secondary contamination in the water distribution pipeline, National institute of environmental (2008). https://scienceon.kisti.re.kr/srch/selectPORSrchReport.do?cn=TRKO201300008764 
  20. H. Y. Kim, Y. T. Noh, H. S. Seo, K. S. Lee, J. C. Jeong and W. C. Kim, Proc. 2019 Korea Studies Information Service System conf., p. 130, Korean society for quality management, Seoul, Korea (2020). https://kiss.kstudy.com/Detail/Ar?key=3822664