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Finite Element Analysis of an Elongation Rolling Process for Manufacturing Seamless Pipes (심리스 파이프 제조를 위한 일롱게이션 공정의 유한요소해석)

  • Jung, Seung Hyun;Shin, Yoo In;Song, Chul Ki
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.10
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    • pp.923-928
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    • 2014
  • Elongation rolling process is an intermediate process to make the uniform thickness and uniform surface roughness during producing seamless pipes. The thickness and surface roughness of seamless pipes are generally affected by the distance of rolls and guide shoes, the roll shape, and its cross angle. In this study, finite element analysis for shape forming process is based on the analysis model of elongation rolling mill with guide shoes. This paper shows how the cross angle of the roll, the rolling rpm, and the distance of the guide shoe influence on the outer diameter and the thickness of seamless pipes. The rolling rpm did not give much influence on outer diameter.

Development of Heat Plate on Butt Welding for PE pipes (PE 배관 맞대기 융착을 위한 열판의 개발)

  • Jin, Hyeong-Guk;Kim, Jae-Seong;An, Dae-Hwan;Lee, Bo-Yeong
    • Proceedings of the KWS Conference
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    • 2006.10a
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    • pp.292-294
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    • 2006
  • Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the butt welding has been paid much attention to joint PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after developing the heat plate of new shape, the PE double wall pipes with misalignments were butt-welded by using the conventional and developed heat plates and comparison of weld-zones and tensile test was performed. As the results of tensile test, weld-zones using developed heat plate have strength of $147.7{\sim}251.0%$ of weld-zones using conventional heat plate.

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Experimental Study on Flow Patterns and Pressure Drop Characteristics of Ice Slurry In Small Size Pipe (1) (소구경 배관내 아이스슬러리의 유동형상 및 압력강하 특성에 관한 실험적 연구(1))

  • 이동원;윤찬일;윤응상
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.5
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    • pp.385-390
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    • 2002
  • To clarify the hydraulic characteristics of ice slurry which made from 6.5% ethylene glycol-water solution flowing through circular pipes of small diameter, experimental studies were performed. The flow pattern was observed and the pressure drop was measured in acrylic pipes with inner diameter of 24 mm. The results of flow visualization revealed that ice particles flowed along the top of pipes in the ranges of small ice fraction and low flow rate, while Ice particles diffused into the whole region of pipes flowed like a homogeneous flow for high flow rate and high ice fraction. An increase in frictional pressure drop was measured as the ice fraction increased in all pipes and unstable flow was observed for up-ward vertical pipe.

Analysis of Failure Probabilities of Pipes in Nuclear Power Plants due to Stress Corrosion Cracking (원자력 발전소 배관의 응력부식에 의한 파손확률 해석)

  • Park, Jai-Hak;Lee, Jae-Bong;Choi, Young-Hwan
    • Journal of the Korean Society of Safety
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    • v.26 no.2
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    • pp.6-12
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    • 2011
  • The failure probabilities of pipes in nuclear power plants due to stress corrosion are obtained using the P-PIE program, which is developed for evaluating failure probability of pipes based on the existing PRAISE program. Leak, big leak and LOCA(loss of coolant accident) probabilities are calculated as a function of operating time for several pipes in a domestic nuclear plant. The sensitivity analysis is also performed to find out the important parameters for the failure of pipes due to stress corrosion. The results show that the steady state oxygen concentration and steady state temperature are important parameters and failure probability is very low when the oxygen concentration is maintained according to the regulation.

Finite Element Analyses for the Estimates of the Burst Pressures of the Pipes with Defects (결함이 있는 배관의 파열압력 예측을 위한 유한요소 해석기법)

  • Kang, Hye-Min;Oh, Chang-Sik;Kim, Yun-Jae
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.305-310
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    • 2008
  • This paper provides the methods to estimate the burst pressures of the pipes with defects, based on finite element analyses. FE codes are frequently adopted for the simulations of the burst tests of the pipes with defects. However, those do not give the burst pressure directly. Because the post-processing should be followed; determination of the fracture strains in accordance with triaxialities, monitoring the strains of pipes, etc. In the present work, these efforts are implemented in the user subroutine UHARD within the general-purpose FE code, ABAQUS. Four fracture criterions are introduced to estimate the burst pressure of pipes, and a simple fracture strain estimate is also developed. FE analyses for the pipe with gouge and corrosion are performed, and the results are compared with the experiment results.

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A Study on the Stress Distribution of Steel Water Pipes(II) - Characteristics of Stress Distribution by External Forces and PWHT - (상수도용 도복장간관의 용접 및 외부하중에 의한 응력 특성에 관한 연구(II) - 복합외부하중 및 후열처리에 따른 용접부의 응력분포 특성 -)

  • 윤석환;이승기;나석주;고명환
    • Journal of Welding and Joining
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    • v.19 no.3
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    • pp.292-297
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    • 2001
  • One of the major characteristics that affects the life of welded steel water pipes is the stress distribution caused by welding and external forces. Some studios have bean carried out on the residual stress of steel water pipes. But the results on the stress distributions by welding and complex external forces are rare, because real water pipes operate under the ground and many kinds of external forces act simultaneously on the joints. To understand the complex stress distributions of welded joints, therefore predictions by numerical or analytic methods are required. In this study, temperature and stress distributions in steel water pipes produced by welding are predicted by a three-dimensional finite element method(FEM). Based on these results, stress distributions by welding and complex external forces are evaluated by adopting the same numerical method. The influence of some post weld heat treatments on residual stress distributions is also investigated.

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Evaluation of Piping Integrity in Thinned Main Feedwater Pipes

  • Park, Young-Hwan;Kang, Suk-Chull
    • Nuclear Engineering and Technology
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    • v.32 no.1
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    • pp.67-76
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    • 2000
  • Significant wall thinning due to flow accelerated corrosion(FAC)was recently reported in main feedwater pipes in 3 Korean pressurized water reactor(PWR) plants. The main feedwater pipes in one plant were repaired using overlay weld method at the outside of pipe, while those in 2 other plants were replaced with new pipes. In this study, the effect of the wall thinning in the main feedwater pipes on piping integrity was evaluated using finite element method. Especially, the effects of both the overlay weld repair and the stress concentration in notch-type thinned area on the piping integrity were investigated. The results are as follows : (1) The piping load carrying capacity may significantly decrease due to FAC. In special, the load carrying capacity of the main feedwater pipe was reduced by about 40% during about 140 months operation in Korean PWR plants. (2) By performing overlay weld repair at the outside of pipe, the piping load carrying capacity can increase and the stress concentration level in the thinned area can be reduced.

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Flow and Heat Transfer Characteristics due to Staggered Arrangement of Heat Pipes in Channels with Heat Pipes and Fins (휜-히트파이프로 구성된 채널에서 히트파이프의 엇갈림배열에 따른 유동 및 열전달 특성)

  • 김성훈;진윤근;김철주
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.11
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    • pp.871-879
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    • 2002
  • The characteristics of flow and heat transfer in the heat exchanger of heat pipes with fins have been studied numerically for cooling enhancement of electronic components of KTX (Korea Train eXpress). Numerical analysis and methodology have been conformed by comparing the experimental results for inlined array of heat pipes. The staggered arrangement of heat pipes has been proposed in order to achieve heat transfer enhancement. As results, the geometry change to the staggered array is conformed to increase the heat transfer of the system accompanied by an increase of pressure drop. The current results of friction factor and Colburn j factor are presented in terms of Reynolds number and staggered distance, and are expected to use for design and manufacture of such a system.

Prediction of Life of Heat Pipes by Measuring Temperature Distribution (온도측정에 의한 히트파이프의 수명예측)

  • Shin, Hung Tae;Polasek, Frantisek;Lee, Yoon Pyo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.7
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    • pp.856-863
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    • 1999
  • The thermal performance degradation of heat pipes is caused by the non-condensable gas generation mainly due to the electrochemical corrosion which results from the reaction of working fluids with tube materials. In this study, a simplified method described below was proposed to estimate the life of heat pipes concerning the non-condensable gas generation. The temperature distributions at the outer surface of heat pipes was measured, and based on them the amount of non-condensable gas of hydrogen was estimated. Applying it to the Arrhenius model, the mass generation of hydrogen and the volume occupied by the gas In heat pipes could be estimated for an operating temperature and time. Moreover, this simplified method was applied to the accelerated life test of nine methanol-stainless steel heat pipe samples.

Measurement of The Thermal Transfer Coefficient Predicting Efficiency of The Heat Pipe (히트파이프 성능예측 열전달계수 측정)

  • Lim, Soo-Jung;Moon, Jong-Min;Rhee, Gwang-Hoon
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2039-2042
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    • 2008
  • Recently, Electronic & Electrical Products have problems how to reduce heat in trend reducing size and increasing speed. heat pipes worked by latent heats can solve problems for effective and quiet electronic applications. Heat Pipes have to be suitably designed for the external conditions due to showing optimum performance. it has influence on efficiency of heat pipes to the exterior structure changed by length, bending angle, diameter. Designing heat pipes has depended on experience from trial and error. this method wasted too many resources, but can't guarantee efficiency. to prevent those wastes, this study aims at making the thermal transfer coefficient predicting efficiency. In this study, the thermal transfer coefficient has been made from experimental results that used variables - lengths between heat source and radiation, bending angles, diameters of heat pipes. variables become non-dimensional in modeling process for making the coefficient.

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