Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Establishment of An Optimal Process to Improve Structural Integrity by Investigating Effect of the Process Variables on Fatigue Lifetime of Steel-Sleeve Repair Welds in Buried Gas Pipeline

매설가스배관 강 슬리브 보수 용접부의 피로수명에 미치는 공정변수 영향 고찰을 통한 최적공정 수립

  • Kim, Jong Sung (Dept. of Nuclear Engineering, Sejong Nat'l Univ.) ;
  • Lee, Cheol (Dept. of Nuclear Engineering, Sejong Nat'l Univ.) ;
  • Kim, Woo Sik (Research and Development Center, Korea Gas Corporation) ;
  • Kim, Ik Jung (Research and Development Center, Korea Gas Corporation)
  • 김종성 (세종대학교 원자력공학과) ;
  • 이철 (세종대학교 원자력공학과) ;
  • 김우식 (한국가스공사 연구개발원) ;
  • 김익중 (한국가스공사 연구개발원)
  • Received : 2017.03.04
  • Accepted : 2017.07.25
  • Published : 2017.11.01
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Abstract

In this study, an optimum process to improve structural integrity was established by investigating effect of the process variables on fatigue lifetime of steel-sleeve repair welds in buried gas pipeline. Residual stresses in the repair welds were derived through sequentially-coupled temperature-stress analysis using ABAQUS, which is a commercial finite element analysis program. In addition, variations of operating stresses were derived by finite element linear elastic stress analysis. Fatigue lifetimes of the steel-sleeve repair welds were evaluated by substituting the derived weld residual stresses and operating stress variations into the structural stress/fracture mechanics approach as input. Parametric study using finite element analysis and fatigue assessment for various repair welding process variables were carried out to investigate the effects of the process variables on the fatigue lifetime. Finally, based on the effects of the process variables on the fatigue lifetime, an optimal process to minimize the welding time and economic costs and to improve the fatigue lifetimes was derived.

본 연구에서는 매설가스배관의 강 슬리브 보수 용접부에 대한 피로수명에 미치는 보수 용접 공정 변수별 영향을 고찰하여 최적 공정을 수립하였다. 상용 유한요소 해석프로그램인 ABAQUS를 이용한 연계 연성 온도-응력 해석을 통해 강 슬리브 보수용접 시 보수용접부에 발생하는 용접 잔류응력을 도출하였다. 또한, 유한요소 선형탄성 응력해석을 통해 운전응력 변이도 도출하였다. 도출된 용접 잔류응력과 운전응력 변이를 입력값으로써 구조응력/파괴역학 접근법에 대입하여 강 슬리브 보수용접부의 피로수명을 평가하였다. 다양한 보수용접 공정 변수에 대한 유한요소해석과 피로평가를 수행하여 공정변수별 피로수명에 미치는 영향을 고찰하였다. 최종적으로는 고찰한 피로수명에 미치는 공정변수별 영항 결과를 토대로 공정 및 경제적 비용을 최소화하고 피로수명을 적절히 향상시킬 수 있는 최적 방안을 도출하였다.

Keywords

References

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