Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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Failure Analysis of Welded type 304 in Cooling Water Pipeline of District Heating System

지역난방 냉각수 배관의 용접부 파손 분석

  • Jeong, Joon-Cheol (Department of AI and Data Science, Ajou University) ;
  • Kim, Woo-Cheol (R&D Institute, Korea District Heating Corp.) ;
  • Kim, Kyung Min (R&D Institute, Korea District Heating Corp.) ;
  • Sohn, Hong-Kyun (The Corrosion Science Society of Korea) ;
  • Kim, Jung-Gu (School of Advanced Materials Science and Engineering, Sungkyunkwan University) ;
  • Lee, Soo-Yeol (Department of Materials Science and Engineering, Chungnam National University) ;
  • Kim, Heesan (Department of Materials Science and Engineering, Hongik University)
  • 정준철 (아주대학교 인공지능.데이터사이언스학과) ;
  • 김우철 (한국지역난방공사 미래개발원) ;
  • 김경민 (한국지역난방공사 미래개발원) ;
  • 손홍균 (한국부식방식학회) ;
  • 김정구 (성균관대학교 신소재공학부) ;
  • 이수열 (충남대학교 신소재공학과) ;
  • 김희산 (홍익대학교 재료공학과)
  • Received : 2020.11.27
  • Accepted : 2020.12.11
  • Published : 2020.12.31
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Abstract

Failure analysis on the welded type 304 pipe used for cooling water piping in the district heating primary side was conducted. Inorganic elements and bacteria in the cooling water and in corrosion products were analyzed, and the weldment was inspected by microscopy and a sensitization test. Corrosion damages were observed in the heat-affected zone, on weld defects such as incomplete fusion or excessive penetration caused by improper welding, or/and at the 6 o'clock position along the pipe axial direction. However, the level of concentration of chloride in the cooling water as low as 80 ppm has been reported to be not enough for even a sensitized type 304 steel, meaning that the additional corrosive factor was required for these corrosion damages. The factor leading to these corrosion damages was drawn to be the metabolisms of the types of bacteria, which is proved by the detection of proton, sulfur containing species, biofilms, and both bacteria and corrosion product analyses.

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References

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