Integrated Expansion Analysis of Pipe-In-Pipe Systems

HAN-SUK CHOI,CHANG-HO DO 한국해양공학회 2006 韓國海洋工學會誌 Vol.20 No.5

This paper presents an analytical method, application of expansion, mechanical design, and integrated expansion design of subsea insulated pipe-in-pipe (PIP) systems. PIP system consists of a flowline and a casing pipe for the transport of high temperature and high pressure product from the subsea wells. To prevent heat loss from the flowline, insulation material is applied between the pipes. The flowline pipe and the casing pipe have mechanical connections through steel ring plate (water stops) and bulkheads. Pipeline expansion is defined by temperature, internal pressure, soil resistance, and interaction force between the flowline and the casing pipe. The results of the expansion analysis, the mechanical design of connection system of the two pipes and tie-in spool design are integrated for the whole PIP system.

수도용 강관의 온도변화에 따른 물리적 특성에 대한 연구

김우영,장암 대한환경공학회 2017 대한환경공학회지 Vol.39 No.12

‘The facilities standards of water supply’ issued by the Ministry of Environment in 2004 indicates that expansion joints cannot be used in welding water supply steel pipes. However, their reason is not clear and it is difficult to confirm the stability of the steel pipe for a water supply pipeline. The purpose of this study is to determine whether or not an expansion joint is necessary to improve the stability of water supply in steel pipe through a displacement analysis of the pipework. The test results are as follows. Firstly, it was found that expansion and contraction of the water supply steel pipe (D 2,400 mm) occur repeatedly in 4 cycles per year, and the maximum expansion and contraction amount of the pipe is 13.03 mm in 1.24 km pipelines. Secondly, the thermal stress caused by expansion and contraction of the steel pipe is 13.7~36.1kgf/cm2 according to the burial depth (0~4 m). The main comparison factors to determine the stability of the steel pipe (STWW 400) were the allowable tensile strength and the fatigue limit, which were computed to be 4,100 kgf/cm2 and 1,840 kgf/cm2, respectively. Finally, the thermal stress of the steel pipe is very small compared to the allowable tensile stress and fatigue stress. Therefore, thermal stress does not affect the stability of the steel pipe, although the expansion and contraction of the steel pipe occurs by temperature changes. In conclusion, the study demonstrated that expansion joints are not required in water supply steel pipelines. 환경부에서 수립한 「상수도 시설기준(2004)」은 관로 신축이음관 설치기준에 있어서는 용접이음 강관에는 설치하지않는 것으로 규정하고 있으며, 이에 대한 근거가 명확하지 않고 관로 안정성이 충분히 확보되었는지 확인하기가 어렵다. 금번 연구에서는 강관의 거동 분석을 통한 관로 안정성을 연구하여 신축이음관의 필요여부를 검증하는 것을 목적으로 하였다. 검토결과는 아래와 같다. 첫째, 아스팔트 도복장강관(D2,400 mm)은 온도변화에 따라 4-cycle로 관로 신‧수축이 반복되며, 연장1.24 km에 있어 최대 13.03 mm의 변위를 나타내었다. 둘째, 수도용 강관의 신․수축으로 발생되는 온도응력은 매설깊이(최대4 m)에 따라 13.7 ~ 36.1 kgf/cm2로 발생되며, 강관(STWW 400)의 안정성에 큰 영향을 키치는 주요 비교인자인 허용 인장강도와 피로한도는 4,100 kgf/cm2와 1,840 kgf/cm2로 산출되었다. 마지막으로, 수도용 강관의 온도응력은 허용 인장강도와 피로한도와 비교시 매우 작음에 따라, 온도변화에 의한 관로의 신․수축이 발생하여도 관로 안정성에는 영향을 끼치지 못함을 알 수있었다. 결론적으로 금번 연구를 통하여 수도용 강관의 관로부에는 신축이음관을 설치할 필요가 없는 것으로 증명되었다.

지중매설관 손상 방지를 위한 콘크리트매트와 팽창매트의 지반보강효과에 관한 실험적 연구

박정준,신희수,유중조,홍기권 한국지반신소재학회 2019 한국지반신소재학회 논문집 Vol.18 No.1

최근 도심지내에서는 지반공동 복구공사, 관로교체 공사 등 생활의 편의성 확보를 위한 소규모 굴착공사가 이루어지고 있다. 본 연구에서는 지중매설관 하부의 미흡한 다짐관리로 인하여 부등침하가 발생할 경우, 관의 파손에 의한 피해를 저감하기위해 관 하부를 보강할 수 있는 방안에 대하여 실험적 연구를 수행하였다. 즉, 콘크리트매트와 팽창매트를 이용한 매설관주변지반의 보강효과에 관한 평판재하시험을 실시하였다. 실험결과, 콘크리트매트와 팽창매트 보강에 따른 지중응력 감소율은재하하중 크기에 따라 각각 약 46%∼48% 및 39%∼42%로 분석되었다. 즉, 콘크리트매트와 팽창매트의 지반보강효과에 기인하여, 연구에 적용된 각각의 재료는 매설관의 침하 및 매설관 하부지반의 변형을 감소시키는 효과가 있는 것으로 판단되었다. 이를 바탕으로 지중매설관 하부지반 또는 매설관 사이의 지반에 콘크리트매트 및 팽창매트를 보강한다면, 지중에서 예측하기어려운 공동발생 및 지반침하에 따른 매설관 손상을 다소 방지할 수 있는 것으로 평가되었다. Recently, small-scale excavation like ground cavity restoration and buried pipe replacement works are being carried out in urban area, in order to improve living convenience. This paper describes experiment results on the ground reinforcement method that can reduce the buried pipe damage, when the differential settlement occurred due to poor compaction of ground below the buried pipe. Plate load tests were conducted to evaluate a reinforcement effect of ground using concrete mat and expansion mat in the ground below the buried pipe. The results showed that the stress reduction ratio by concrete mat and expansion mat according to the surcharge load was about 46%∼48% and 39%∼42%, respectively. Therefore, the differential settlement of the buried pipe and the ground deformation below the buried pipes were reduced by the reinforcement effect of the concrete mat and expansion mat. This means that it is possible to prevent a buried pipe damage due to underground cavity and ground subsidence, if concrete mat and expansion mat are reinforced in the ground below the buried pipe or on the ground between the buried pipes.

Effects of expansion pipe length on heat transfer enhancement of impinging jet array

Kirttayoth Yeranee,Makatar Wae-hayee,Ibroheng Piya,Yu Rao,Chayut Nuntadusit 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.5

We experimentally and numerically investigated the effect of expansion pipe length on heat transfer enhancement and flow characteristics of impinging jet array with mounting expansion pipe. The inner diameter (d) and the length of each main pipe nozzle was d = 17.2 mm and 200 mm, respectively. Nozzle arrangement was distributed in 5 rows × 5 columns with an in-line configuration. The jet-to-wall distance (H) was fixed at H/d = 8, while the jet-to-jet spacing (S) was varied at S/d = 6 and 8. The expansion pipe length (L) was varied at L/d = 4, 6 and 8, and the inner diameter of the expansion pipe (D) was fixed at D/d = 4. Reynolds number of the jets was kept constant at 30000. The conventional impinging jets were also performed to compare with the case of jets with mounting expansion pipe. The 3-D numerical simulation with v 2 -f turbulence model was applied to simulate the flow characteristics. Results showed that the surrounding air was induced into the expansion pipe, and an entrainment of induced air became greater when expansion pipe was longer. This influenced more markedly on enhancement of Nusselt number at stagnation point for narrow jet-to-jet spacing (S/d = 6).

상수관 및 하수관 손상에 의한 도로함몰 특성에 관한 모형실험

최석일,권기철 한국도로학회 2019 한국도로학회논문집 Vol.21 No.1

PURPOSES: The purpose of this study is to identify the mechanism of road subsidence caused by damaged water and sewer pipes. METHODS: A series of soil chamber test using damaged water and sewer pipe models were conducted under various conditions. RESULTS : Characteristics of cavity expansion and collapse caused by damaged pipes were affected by the damaged location in the sewer pipe, the head on the water pipe, the distance between the damaged water pipe and outlet, and relative soil density. CONCLUSIONS: Sewer-pipe damage was considered a direct cause of road subsidence, and the cavity expanded discontinuously. When the outlet was located under the damaged water pipe, the cavity expanded in the water pipe’s direction, and collapse occurred above the pipe. However, when the outlet was located atop the damaged water pipe, the cavity expanded toward the outlet direction and resulted in a subsidence. Cavity expansion speed was affected by various conditions, such as the pipe’s water head, outlet position, distance between the damaged water pipe and outlet, and relative soil density. However, the cavity expansion shape did not affect factors, except for outlet position.

상계법과 유한요소법을 이용한 확관금형 설계

조용일(Yong-Il Cho),김승환(Seung-Hwan Kim),추연근(Yuan-gen Qiu),조해용(Hae-Yong Cho) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.5

Pipe expansion involves various methods to enlarge the diameter of the pipes with the use of a mandrel or punch placed inside the pipe. In this study, the upper bound method was used to analyze the pipe expanding process as well as design a die. A kinematically admissible velocity field was derived for the upper bound analysis with the occurrence of pipe thinning during the expansion factored in. The analysis confirms that a semi-cone angle of the punch between 15ween pip is most advantageous for pipe expansion. The results of the upper bound analysis, which were also consistent with those of the FEM, can be useful for the design of a pipe expansion die.

A Review of the Expansion Behavior of Marine Pipelines

HAN-SUK CHOI,SEUNG-KEON LEE,EUN-JEE CHUN 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.2

A camprehensive review of the expansion behavior of marine pipelines due to thermal and pressure change is presented based on research work over the last 10 years. The review is organized into five main sections, namely free expansion with uniform temperature, free expansion with temperature gradient, expansion with end restraints, expansion of pipe-in-pipe system, and lateral deviation (snaking). Based on the accumulated knowledge of the interactions between the soil and pipeline behavior, a whole pipeline system can be modeled by an accurate finite element method (FEM). This methodologoy requires a comprehensive understanding and engineering verification of the expansion behavior of marine pipelines.

Expansion Analysis of Subsea Pipe-In-Pipe Due to High Temperature and High Pressure Product

HAN­SUK CHOI(최한석),HYUN-MO SON(손현모),SI-YOUNG KIM(김시영) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.5

본 논문은 고온 고압의 유류 수송용 이중배관의 팽창에 대한 해석적 방법에 대한 결과고찰과 해석, 그리고 설계시 응용이 가능한 현상에 대해 논하였다. 고온의 유류수송시 온도를 유지할 목적으로 내부의 수송 배관과 외부의 케이싱 배관사이에 절연체가 쓰여진다. 이런 이중배관의 팽창을 조사할 수 있는 간단한 해석적 방법이 개발되었다. 본 논문에서는 온도의 분포, 압력, 토질의 저항, 수송배관과 케이싱배관과의 상호작용 등이 고려되어졌으며, 이 해석적 방법은 심해의 이중배관 해석에 적합하게 개발되었다. 계산의 결과 분석에서 고온의 영향이 고압보다 현저한 것이 밝혀졌다.

다중 적층형 금속 벨로우즈 신축관이음의 내진성능 시험

전법규,김성완,윤다운,주부석,유진석 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.4

Pipelines are representative infrastructure facilities. Damage to pipelines caused by earthquakes is highly to cause serious damage for city. Therefore, pipeline need to be protected from earthquakes. But large relative displacements exceeding the allowable displacement of pipe can be caused by earthquakes. This seismic behaviors could causes damage to the joint of the pipe. The seismic performance of the pipe can be improved by applying a seismic separation joint to a location where excessive deformation of the pipe may occur. The multi-ply metal bellows has good durability against low-cycle fatigue loads such as earthquakes. Therefore multi-ply metal bellows could be used as seismic separation joint of pipes. In this study, Experimental study was performed for multi-ply metal bellows which is the one of seismic separation joint. Monotonic and cyclic loading tests were performed on two types of multi-ply metal bellows and limit state was estimated. The difference of leakage displacement in the monotoinc loading tests are less than 2%. However, the leakage displacement of the cyclic loading tests showed a difference of more than 12%. As a result, more layers of bellows could improve the performance for cyclic loading of multi-ply metal bellows. 배관시스템은 대표적인 사회기반시설이다. 지진으로 인한 배관 손상은 심각한 피해를 초래할 수 있으므로 배관시스템은 지진으로부터 반드시 보호되어야 할 필요가 있다. 지진은 설계기준을 초과하는 상대변위를 동반할 수 있다. 이러한 지진의거동은 배관 이음부에 손상을 줄 수 있다. 배관시스템에서 과도한 변형이 발생할 수 있는 위치에 지진분리이음을 적용하면 내진성능을 향상시킬 수 있다. 적층형 금속 벨로우즈는 지진과 같은 저주기 피로 하중에 대한 내구성이 우수하다. 따라서 다중 적층형 금속 벨로우즈는 파이프의 면진 이음새로 사용할 수 있을 것으로 판단된다. 본 연구에서는 지진분리이음의 하나인 다중 적층형 금속 벨로우즈에 대한 실험적 연구를 수행하였다. 2종류의 다중 적층형 벨로우즈 신축관이음에 대하여 단조하중 및 반복하중재하시험을 수행하고 손상모드와 한계상태를 추정하였다. 그리고 단조재하시험과 반복재하시험의 결과를 비교 분석하였다.

Analysis of the Propagation Characteristics of Ultrasonic Guided Waves Excited by Single Frequency and Broadband Sources

강토,송성진,조영도,이동훈,조현준,김학준 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.6

Excitation and propagation of guided waves are very complex problems in pipes due to their dispersive nature. Pipes are commonly used in the oil, chemical or nuclear industry and hence must be inspected regularly to ensure continued safe operation. The normal mode expansion(NME) method is given for the amplitude with which any propagating waveguide mode is generated in the pipes by applied surface tractions. Numerical results are calculated based on the NME method using different sources, i.e., non-axisymmetric partial loading and quasi-axisymmetric loading sources. The sum of amplitude coefficients for 0~nineth order of the harmonic modes are calculated based on the NME method and the dispersion curves in pipes. The superimposed total field which is namely the angular profile, varies with propagating distance and circumferential angle. This angular profile of guided waves provides information for setting the transducer position to find defects in pipes.