Safety evaluation of socket weld integrity in nuclear piping

Young Hwan Choi, Sun Yeong Choi, Yun Jae Kim, Young Jin Kim, Hho Jung Kim

Research output: Contribution to journalConference article

7 Citations (Scopus)

Abstract

The purposes of this paper are to evaluate the integrity of socket weld in nuclear piping and prepare the technical basis for a new guideline on radiographic testing (RT) for the socket weld. Recently, the integrity of the socket weld is regarded as a safety concern in nuclear power plants because lots of failures and leaks have been reported in the socket weld. The root causes of the socket weld failure are known as unanticipated loadings such as vibration or thermal fatigue and improper weld joint during construction. The ASME Code Sec. III requires 1/16 inch gap between the pipe and fitting in the socket weld. Many failure cases, however, showed that the gap requirement was not satisfied. The Code also requires magnetic particle examination (MT) or liquid penetration examination (PT) on the socket weld, but not radiographic examination (RT). It means that it is not easy to examine the 1/16 inch gap in the socket weld by using the NDE methods currently required in the Code. In this paper, the effects of the requirements in the ASME Code Sec. III on the socket weld integrity were evaluated by using finite element method. The crack behavior in the socket weld was also investigated under vibration event in nuclear power plants. The results showed that the socket weld was very susceptible to the vibration if the requirements in ASME Code were not satisfied. The constraint between the pipe and fitting due to the contact significantly affects the integrity of the socket weld. This paper also suggests a new guideline on the RT for the socket weld during construction stage in nuclear power plants.

Original languageEnglish
Pages (from-to)1725-1730
Number of pages6
JournalKey Engineering Materials
Volume270-273
Issue numberIII
DOIs
Publication statusPublished - 2004
EventProceedings of the 11th Asian Pacific Conference on Nondestructive Testing - Jeju Island, Korea, Republic of
Duration: 2003 Nov 32003 Nov 7

Keywords

  • Gap
  • Nuclear Power Plant
  • Socket Weld
  • Stress Intensity Factor
  • Weld Leg

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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