• 제목/요약/키워드: Thick Pipe

검색결과 59건 처리시간 0.027초

후육 용접 강관의 HIC 저항성 평가 (Evaluation of HIC Resistance for Thick-wall Welded Pipe)

  • 서준석;김희진;유회수
    • Journal of Welding and Joining
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    • 제23권3호
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    • pp.34-39
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    • 2005
  • It is required for the steel materials used in the sour environment to have sufficient resistance to hydrogen induced cracking(HIC). For line pipe steels, HIC resistance could be varied during pipe making process due to the large plastic deformation applied in the thick-wall pipe. In order to figure out such effect, HIC tests were performed not only in the plate condition but in the pipe condition and their results were compared in terms of cracking ratio. Test results demonstrated a detrimental effect of plastic deformation to HIC resulting in a substantial increase in the cracking ratio after pipe forming process. All of the cracks found in the pipe material were located in the outer layer of pipe where the tensile strain was resulted during pipe forming stage. In order to understand the HIC resistance of the pipe but in the plate condition, it was suggested to pre-strain the plate to some extent before the HIC test.

An Improved Pipe Hoop Stress Formula

  • Lee, Jaeyoung
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2001년도 춘계학술대회 논문집
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    • pp.76-82
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    • 2001
  • The ASME B3l.4〔1〕and B3l.8 〔2〕codes use the thin wall formula to predict hoop stress in a pipe. To account for the external pressure, the above codes simply subtract the external pressure from the internal pressure. The thin wall formula using this differential pressure does not give the same hoop stress as the thick wall formula. This paper proposes an improved equation to predict pipe hoop stress subjected to both internal and external pressure. Compared to the conventional thin wall formula, the improved formula has additional terms, which improve the agreement with the thick wall formula and account for external pressure. The improved formula is less conservative than the conventional thin wall formula, but slightly more conservative than the thick wall formula. The formula is simpler and easier to use than the thick wall formula and will save pipe material cost as well as installation cost compared to using the conventional thin wall formula. The savings will increase as the water depth increases.

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프레스-브레이킹 굽힘 공정을 이용한 SAW 후육강관의 외경 예측을 위한 해석적 연구 (Numerical Prediction of the Outer Diameter for SAW Pipes Formed by Press-Brake Bending)

  • 박기범;강병권;강범수;구태완
    • 소성∙가공
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    • 제25권2호
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    • pp.116-123
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    • 2016
  • Press-brake bending is used to shape flat and thick plates into a targeted circular configuration without excessive localized thinning or thickening. A brake bending press called 'a knife press bending apparatus' has been widely adopted to manufacture thick, large and long pipe from initially thick plate. Submerged Arc Welded (SAW) pipes are also produced by employing press-brake bending. These pipes are mainly used for oil, natural gas and water pipelines. The principal process variables for press-brake bending can be summarized as stroke of the press-brake knife, the distance between both roll in the lower die, and the feeding length of the plate. Many combinations of these process variables are available, thus various pipe diameters can be realized. In the current study, a series of repetitive numerical simulations by feeding a thick plate with initial thickness of 25.4mm were conducted with the consideration of elastic recovery. Furthermore, an index for SAW pipe production is proposed which can be widely used in industry.

두꺼운 배관에 존재하는 축방향 경사관통균열의 탄성파괴역학 매개변수 계산 (Estimates of Elastic Fracture Mechanics Parameters for Thick-Walled Pipes with Slanted Axial Through-Wall Cracks)

  • 한태송;허남수
    • 대한기계학회논문집A
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    • 제36권12호
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    • pp.1521-1528
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    • 2012
  • 본 논문에서는 두꺼운 배관에 존재하는 축방향 경사관통균열의 탄성응력확대계수 및 탄성 균열열림변위 해를 제시하였다. 이를 위해 배관의 두께, 기준균열길이, 경사관통균열 길이비를 체계적으로 변화시키며 3차원 탄성 유한요소해석을 수행하였다. 하중조건으로는 균열 성장에 영향을 미치는 내압을 고려하였다. 유한요소해석 결과를 바탕으로 두꺼운 배관에 존재하는 이상적인 축방향 관통균열과 경사관통균열에 대한 탄성응력확대계수와 탄성 균열열림변위를 균열선단 및 두께를 따라 제시하였다. 특히 응력확대 계수의 경우에는 이상적인 축방향 관통균열 결과로부터 쉽게 경사관통균열의 응력확대계수를 구할 수 있는 경사관통균열 보정계수를 제시하였다.

Brake Bending Press 구조 건전성에 관한 연구 (A Study on Structural Integrity of Brake Bending Press)

  • 박중원;이현민;김상목;구태완;강범수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2008년도 추계학술대회 논문집
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    • pp.190-193
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    • 2008
  • Thick pipes which have large thickness have been used in fields of ocean and industrial plants, and for oil pipelines, water pipes and pipe arrangement. In manufacture of the pipes, roll bending process has been used mostly. However, studies on the pipe forming processes using brake press have been performed in recent days. Normally, the brake press has high aspect ratio, so analysis of structural integrity should be conducted. In this study, the evaluation of structural integrity of the brake bending press was carried out for thick pipe forming process.

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10,000 Ton Brake Bending Press 구조 건전성에 관한 평가 (Structural Integrity Evaluation of 10,000 Ton Brake Bending Press)

  • 박중원;이현민;구태완;김정;강범수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.529-533
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    • 2008
  • Thick pipes have been used in fields of ocean and industrial plants, and pipe arrangement of oil and water pipelines. Mostly, roll bending process has been used in manufacture of the pipes. Recently, however, studies on the pipe forming processes using brake press have been performed. Normally, the brake press has high aspect ratio, so structural integrity evaluation should be conducted. In this study, finite element analysis of structural integrity for the brake bending press was carried out for thick pipe forming process.

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Knife Press Forming 공정의 후육관 성형성 예측 (Estimation on Formability of ]Knife Press Forming Process for the Thick Pipes)

  • 박중원;노학곤;구태완;강범수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2009년도 추계학술대회 논문집
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    • pp.319-322
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    • 2009
  • Roll bending process has been used for manufacturing the pipes. However, it is not suitable process for the thick pipes. Knife press forming is acceptable process for the thick pipes. Recently, the knife press forming process using brake bending press have been performed. In this study, the estimation on formability of knife press forming process for the thick pipes is carried out. From the results, it is ensured that the thick pipes could be obtained by the knife press forming process.

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박판강대의 롤성형 및 부하 분석 (Thin Steel Sheet Roll Forming and Load Analysis)

  • 서정현
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1999년도 춘계학술대회논문집
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    • pp.273-279
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    • 1999
  • In this paper the stress and strain behaivor in near homogeneous isotropic matrix of metal like steel was studied roll forming of thin steel sheet for cylindrical pipe. Analytical results reveals a body which is on the area of square thickness along and perpendicular to the width of thin steel sheet is in the state of plane strain during roll forming. As a result construction of analytical method for calculating deformation load and stably deformed length along the width of strained steel sheet was established. Also loads applied during roll forming were analyzed using two typical thin steel sheet 12.3m thick steel sheet with 42.5kg /mm2 yield strength of pipe and 5.3mm thick steel sheet with 32.5kg/mm2 yield strength of pipe. Through this analysis applicability of the analytical method for deformation load during roll forming of cylindrical thin steel pipe was evaluated with a study of necessary production technology for roll forming and design technology for roll forming machine.

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박판 강대의 롤성형 및 부하 분석 (Thin Steel Sheet Roll Forming and Load Analysis)

  • 서정현
    • 소성∙가공
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    • 제8권6호
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    • pp.554-562
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    • 1999
  • In this paper, the stress and strain behavior in near homogeneous isotropic matrix of metal like steel was studied during roll forming of thin steel sheet for cylindrical pipe. Analytical result reveals a body which is on the area of square thickness along and perpendicular to the width of thin steel sheet is in the state of plane strain during roll forming. As a result, construction of analytical method for calculating deformation load and stably deformed length along the width of strained steel sheet was established. Also, loads applied during roll forming were analyzed using two typical thin steel sheets. 12.3mm thick steel sheet with 42.5kg/㎟ yield strength of pipe and 5.3mm thick steel sheet with 32.5kg/㎟ yield strength of pipe. Through this analysis, applicability of the analytical method for deformation load during roll forming of cylindrical thin steel pipe was evaluated with a study of necessary production technology for roll forming and design technology for roll forming machine.

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A Boundary Element Solution Approach for the Conjugate Heat Transfer Problem in Thermally Developing Region of a Thick Walled Pipe

  • Choi, Chang-Yong
    • Journal of Mechanical Science and Technology
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    • 제20권12호
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    • pp.2230-2241
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    • 2006
  • This paper presents a sole application of boundary element method to the conjugate heat transfer problem of thermally developing laminar flow in a thick walled pipe when the fluid velocities are fully developed. Due to the coupled mechanism of heat conduction in the solid region and heat convection in the fluid region, two separate solutions in the solid and fluid regions are sought to match the solid-fluid interface continuity condition. In this method, the dual reciprocity boundary element method (DRBEM) with the axial direction marching scheme is used to solve the heat convection problem and the conventional boundary element method (BEM) of axisymmetric model is applied to solve the heat conduction problem. An iterative and numerically stable BEM solution algorithm is presented, which uses the coupled interface conditions explicitly instead of uncoupled conditions. Both the local convective heat transfer coefficient at solid-fluid interface and the local mean fluid temperature are initially guessed and updated as the unknown interface thermal conditions in the iterative solution procedure. Two examples imposing uniform temperature and heat flux boundary conditions are tested in thermally developing region and compared with analytic solutions where available. The benchmark test results are shown to be in good agreement with the analytic solutions for both examples with different boundary conditions.