Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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Failure Analysis of Air Vent Connected with Heat Supply Pipeline Under Manhole

맨홀에 설치된 지역난방 열공급관 에어벤트의 전단부 파손 원인 규명

  • Cho, Jeongmin (Department of Materials Science and Engineering, Chungnam National University) ;
  • Chae, Hobyung (Department of Materials Science and Engineering, Chungnam National University) ;
  • Kim, Heesan (Department of Materials Science and Engineering, Hongik University) ;
  • Kim, Jung-Gu (School of Advanced Materials Science and Engineering, Sungkyunkwan University) ;
  • Kim, Woo Cheol (R & D Institute, Korea District Heating Corp.) ;
  • Jeong, Joon Cheol (R & D Institute, Korea District Heating Corp.) ;
  • Lee, Soo Yeol (Department of Materials Science and Engineering, Chungnam National University)
  • 조정민 (충남대학교 신소재공학과) ;
  • 채호병 (충남대학교 신소재공학과) ;
  • 김희산 (홍익대학교 재료공학과) ;
  • 김정구 (성균관대학교 신소재공학부) ;
  • 김우철 (한국지역난방공사 미래개발원) ;
  • 정준철 (한국지역난방공사 미래개발원) ;
  • 이수열 (충남대학교 신소재공학과)
  • Received : 2020.07.14
  • Accepted : 2020.07.29
  • Published : 2020.08.31
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Abstract

The air vent connected to a heat supply pipeline in the district heating system has been used to eliminate the existing air in the pipe, which has a detrimental effect on corrosion durability and heat efficiency. Recently, the air vent installed under a manhole for 22 years was corroded and several pinholes were detected in the front-end of the air vent. To identify the cause of the failure, thickness reduction, corrosion products, and water quality were examined. The corrosion damage was significant at the outside of the front-end of the air vent where the insulator was covered. While a thin oxide layer was formed in the interior of the tube, the coarse and porous corrosion products consisting of magnetite and hematite were found externally. Water flowing into the thermal insulator was absorbed by the insulator following hydrolysis. The hydrolyzed insulator ejected the corrosion factors such as Cl-, SO42-, and NH4+. The findings suggest that the corrosion under insulation due to rain water is the main cause of the underlying failure in the air vent.

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References

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