• 한국산업융합학회 논문집
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• 제8권4호
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• pp.197-204
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• 2005

It is well known that pipelines have the highest capacity and are the safest and least environmentally disruptive form of transporting oil and gas. However, pipeline damages caused by both internal and external corrosion is a major concern threatening the reliability of oil and gas transportation and the soundness of pipeline structure. In this study, we estimated the expected allowable damage defect by comparing the ASTM B31G code which has been developed as the evaluation method of reliability and incident prevention of damaged pipelines based on the amount of loss due to corrosion and the yield strength of materials to a modified theory considering diverse detailed corrosional forms. Furthermore, we suggested the method that estimates the expected life span of used pipelines by utilizing the reliability method based on major variables such as, the depth and length of damage and corrosional rate affecting the life expectancy of pipelines.

• 한국안전학회지
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• 제21권2호
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• pp.1-6
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• 2006

It is well known that pipelines have the highest capacity and are the safest and least environmentally disruptive form of transporting oil and gas. However, pipeline damage caused by both internal and external corrosion is a major concern threatening the reliability of oil and gas transportation and the soundness of the pipeline structure. In this study, we estimate the allowable damage by comparing the ASTM B31G code to a modified theory considering diverse detailed corrosive forms. The ASTM B31 G code has been developed as the evaluation method for reliability and incident prevention of damaged pipelines based on the amount of loss due to corrosion and the yield strength of materials. Furthermore, we suggest a method for estimating the expected life span of used pipelines by utilizing the reliability method based on major variables such as the depth and length of damage and the corrosion rate affecting the life expectancy of the pipelines.

• 한국압력기기공학회 논문집
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• 제5권2호
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• pp.20-26
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• 2009

The dominant incidents category for onshore and offshore natural gas transmission pipelines in the world is associated with outside forces. Incidents in the outside forces category embrace acts of nature, which typically cause widespread structural damage, as well as act of man, whose effects tend to cause dents and/or gouges localized at point of contact that are referred to as mechanical damage. Therefore, these damage types must be better addressed to avoid unnecessary and costly repairs and the possibility of catastrophic events. First of all, the characterizing features of mechanical damage in gas pipelines were evaluated by using of excavator or boring machine. There is no reliable method for evaluating the safe operating pressure of pipeline affected by mechanical damage. It is especially important to evaluate the remaining strength of damaged pipelines due to outside force. Therefore, the full scale burst tests were conducted to evaluate the remaining strength of pipe with mechanical damage that combines a dent and a gouge. This paper is supposed to provide information that will assist in developing a criterion to assess serviceability in pipelines with mechanical damage.

• International Journal of Safety
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• 제6권2호
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• pp.43-48
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• 2007

We introduced the Excavation One Call System (EOCS) as a pilot system, in Seoul, Korea. The system utilizes the phone and internet to transfer information about digging underground and buried gas pipelines, although currently written forms are used in accordance with the City Gas Business Law. After one year, we evaluated the business model by surveying the excavators and the operators of the gas companies. This paper shows that the EOCS was more effective in preventing the buried gas pipelines from being damaged than the existing method that has to use due form. It also shows that the EOCS was more convenient and cost efficient than the present policies in place. We come to the conclusion that the EOCS should be extended nationwide and gradually include other subsurface facilities.

• 상하수도학회지
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• 제10권1호
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• pp.96-111
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• 1996

The failure of water pipelines is progressed by several compound factors and the collection and analysis of data about pipeline failure are inevitable for effective pipeline rehabilitation. Data analysis of pipeline failure was already performed in USA and Europe. Based on such phenomena, failure characteristics about metropolitan pipelines in Korea were analyzed: The conclusions of this study are as followings. 1. The failure cause of pipelines can be classified into natural cause and artificial cause. Artificial cause is 32% of total causes, so artificial failure as several constructions happens frequently in Korea. Although the failure by old pipe is greatest of any other causes m classtfied cause, failure cause is not classified in detail now. 2. The damaged part of pipelines is affected by cities, distribution system inventory, bedding conditions, and so on. In this study, the failure of pipeline body(67%) is greater than the failure of pipeline joint(33%) in natural failure. 3. In regard to pipe materials, failure rate of DCIP(0.8456), PEP(0.7288), and GSP(0.6643) is greater than that of CIP(0.3985) and CWSP(0.2348). 4. Usually, faIlure rate is increased in proportion to diameter of pipeline. In this study, CIP, DCIP, and CWSP have clear trends. But the trends of PEP is reverse, the case of GSP, HP is obscure due to data shortage. 5. There are no direct relationships between burial age and failure rate of pipelines. 6. Annual breaks and winter(Nov.~Feb.) breaks of pipelines are investigated. As a result, WInter breaks to annual breaks of CIP is 51.3%(Seoul), 51.1%(Taegu),38.7%(Pusan). This phenomena have direct correlation with average winter temp. of cities.

• Geomechanics and Engineering
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• 제37권2호
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• pp.189-195
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• 2024

Buried pipelines can be classified as continuous and segmented pipelines. These infrastructures can be damaged either by ground movement or by seismic wave propagation during an earthquake. Permanent ground deformations (PGD) include surface faulting, liquefaction-induced lateral spreading and landslide. Liquefaction is a major problem for both superstructures and infrastructures. Buyukcekmece lake zone, which is the studied region in this paper, is a liquefaction prone area located near the North Anatolian Fault Line. It is an active fault line in Turkey and a major earthquake with a magnitude of around 7.5 is expected in this investigated region in Istanbul. It is planned to be constructed a new 12" steel natural gas pipeline from one side of the lake to the other side. In this study, this case has been examined in terms of two different support conditions. Firstly, it has been defined as a beam in liquefied soil and has built-in supports at both ends. In the other approach, this case has been modeled as a beam in liquefied soil and has vertical elastic pinned supports at both ends. These models have been examined and some solution proposals have been produced according to the obtained results. In this study, based on this sample, it is aimed to determine the behaviors of buried continuous pipelines subject to liquefaction effects in terms of buoyancy.

• 한국가스학회지
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• 제20권5호
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• pp.72-81
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• 2016

매설된 강관의 피복이 손상되는 경우에는 부식이 발생할 수 있고, 부식으로 인한 핀홀이 발생하여 가스누출사고가 발생할 수도 있다. 미국과 영국 등 국외에서는 이를 방지하기 위하여 DCVG 또는 ACVG 등을 이용하여 매설된 배관의 피복손상을 탐측하고 이상부위에 대하여 직접 굴착을 통해 배관외면부식여부 등을 확인하고 필요시에는 보수를 하고 있다. 이를 외면부식 직접평가법(ECDA)이라 하며, NACE 기준 등에서 ECDA에 대한 기준을 규정하고 있다. 국내의 경우에는 2014년 중압배관의 정밀안전진단 제도를 도입하면서 KGS 코드에 외면 부식직접평가에 대한 내용을 포함하여 규정하고 있다. 본 연구에서는 매설배관의 외면부식을 탐측할 수 있는 장비를 개발하고, 개발된 장비의 실증시험을 위한 배관시험장을 구축하였다. 또한, 개발된 장비의 성능을 입증하기 위하여 배관 시험장에서 현장 실증시험을 실시하였다. 현장 실증 시험은 개발된 장비와 국내에 도입되어 사용중인 국외 장비와의 피복결함 탐측 성능 비교시험으로 실시하였다. 개발한 장비를 이용하여 매설배관 탐측 시험을 실시한 결과, 개발한 장비는 미국이나 영국에서 개발되어 국내에 보급되어 사용중인 장비에 비해 훨씬 사용이 편리하고 성능이 우수함을 확인할 수 있었다.

• Journal of Magnetics
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• 제16권1호
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• pp.36-41
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• 2011

If gas is leaking out of gas pipelines, it could cause a huge explosion. Accordingly, it is important to ensure the integrity of gas pipelines. Traditionally, over the years, gas-operating companies have used the ILI system, which is based on axial magnetic flux leakage (MFL), to inspect the gas pipelines. Relatively, there is a low probability of detection (POD) for the axial defects with the axial MFL-based ILI. To prevent the buried pipeline from corrosion, it requires a protective coating. In addition to the potential damage to the coating by environmental factors and external forces, there could be defects on the damaged coating area. Thus, it is essential that nondestructive evaluation methods for detecting axial defects (axial cracks, axial groove) and damaged coating be developed. In this study, an electromagnetic acoustic transducer (EMAT) sensor was designed and fabricated for detecting axial defects and coating disbondment. In order to validate the performances of the developed EMAT sensor, experiments were performed with specimens from axial cracks, axial grooves, and coating disbondment. The experimental results showed that the developed EMAT sensor could detect not only the axial cracks (minimum 5% depth of wall thickness) and axial grooves (minimum 10% depth of wall thickness), but also the coating disbondment.

• 한국가스학회지
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• 제18권2호
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• pp.62-68
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• 2014

도시가스 배관의 현행 보수 방법으로는 육성 용접, 슬리브 용접과 같은 용접을 이용한 방법 이외에 탄소 섬유나 유리 섬유 복합 재료를 사용한 보수 방법이 해외에서 사용되고 있다. 우리 나라의 경우도 도시가스 배관 안전관리의 중요성이 대두되면서 자체보수규정을 마련할 필요성이 있다. 해외의 사례로서 이미 연구가 상당부분 이루어진 용접에 의한 보수 방법이 아닌 비교적 새로운 보수 방법인 복합재로 보수 방법에 대한 연구가 필요한 시점이다. 본 논문에서는 복합재료 보수배관의 안정성 평가의 기본 단계로서 탄소 섬유 복합재료를 사용하여 보수한 가스 배관의 유한 요소법을 이용한 구조 해석을 수행하였고 결과에 대해 고찰해 보았다.

• 한국가스학회지
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• 제10권3호
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• pp.20-26
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• 2006

본 연구에서는 교량에 부착된 도시가스 배관 53개소에 대해 현장조사를 실시하고 위해요인이 발생할 우려가 있는 도시가스배관 대해 구조해석 프로그램을 이용한 응력분석을 실시하고 취약부위에 대한 현장 응력 측정을 통해 배관에 미치는 응력에 관한분석을 실시하여 가스배관의 안전성을 평가하고자 했다. 현장 안전진단의 결과는 일차적으로 선정된 대상 10개소 중 가장 응력적으로 취약할 것으로 판단되는 2개소에 대해 현장 응력측정을 통한 진단을 수행하였다. 안전계수 2를 고려한 배관 최대 지지응력의 70% 이상 수준의 응력이 부가되는 것으로 나타났다. 보수시점을 넘어선 교량첨가배관에 대해 응력 해소 공사, 지지대 보수 및 교체 공사를 통해 부가되는 응력을 해소하였다. 현장진단 결과로 나타난 바와 같이 장기간 경과된 배관에서도 견고한 고전으로 발생하는 응력은 보수를 통하여 해소해줌으로 안전성을 확보할 수 있었다.