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안준태(Jun Tae Ahn),한상욱(Sang Uk Han),이경철(Kyung Chul Lee),한승호(Seung Ho Han) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Valves are one of the important equipments of pipe-line system in nuclear power plant, which structural safety under seismic loads should be verified experimentally. The experimental verification makes it difficult that modification of configuration and performance of the parts of valves is carried out simply through an optimal design procedure. Recently, numerical analysis has been performed intensively before the experimental verification, so that appropriated design variables satisfying performances under the seismic loads can be found. In this study numerical structural analysis of 200A butterfly valve for nuclear power plant was performed according to KEPIC MFC to provide static and dynamic analysis. The static analysis considering an equivalent static load under SSE condition shows the applied stress of 158MPa. In addition, the dynamic analysis provided 183MPa where CQC method by using response spectrums was taken into account. These values are under the allowable strength of used materials for the butterfly valve, so that the structural safety is verified KEPIC MN.
초저온 버터플라이 밸브용 탄성 메탈실의 누설방지에 관한 연구
안준태(Jun-Tae Ahn),이경철(Kyung-Chul Lee),한승호(Seung-Ho Han) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
For the development of a butterfly valve used in LNG vessels, the seat tightness is one of the important factors which should be taken into account in a valve design process. An O-ring type metal seal with a retaining ring showing a high performance of the seat tightness in cryogenic temperature has been widely used despite of high manufacturing cost. As an alternative, a flexible solid metal seal offers not only sufficient tightness of the butterfly vale meeting a requirement of specification, but also relatively low manufacturing cost. In this study, the characteristics of the cryogenic butterfly valve with the flexible solid metal seal, such as flow coefficient and pressure loss coefficient, were estimated by a numerical analysis. In addition, a design criterion to ensure the seat tightness of the butterfly valve in bi-directional flows was proposed. Via a structural analysis, the contact pressure can be calculated by the simulation of a frictional contact behavior on the surface of the metal seal and valve disc. The geometry of the flexible solid metal seal was proposed that satisfies the design criterion for sufficient seat tightness in bi-directional flows, and it was verified by the experiments according to BS6755 and BS6364.
초저온 버터플라이 밸브용 탄성 메탈실의 누설방지에 관한 연구
안준태(Jun Tae Ahn),이경철(Kyung Chul Lee),이용범(Yong Bum Lee),한승호(Seung Ho Han) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.6
LNG 선박에 사용되는 초저온용 버터플라이 밸브의 개발에 있어, 누설검증은 가장 중요한 설계공정 중 하나이다. 초저온에서 누설방지가 가능한 실로서 인코넬 스프링과 같은 탄성지지체가 포함된 O-링 형태의 메탈실이 널리 사용되고 있으나, 제작비가 고가인 단점을 갖고 있다. 이에 대한 대안으로 부가적인 탄성지지체 없이도 누설조건을 만족시키며, 제작비가 저렴한 탄성 메탈실의 개발이 요구되고 있다. 본 연구에서는 탄성 메탈실의 누설방지를 위한 설계조건을 정립하여, 초저온 및 고압환경에서 누설방지가 가능한 탄성 메탈실의 형상을 수치해석을 통해 고찰하였다. 아울러 이를 기반으로 시제품을 개발하고, 상온 및 초저온 상태에서 BS6755 및 BS6364 에 준하는 누설시험을 실시하여 누설여부를 확인하였다. For the development of butterfly valves used in liquefied natural gas (LNG) vessels, the seat tightness is one of the important factors to be taken into account in the valve-design process. An O-ring-type metal seal with a retaining ring showing good seat tightness at cryogenic temperatures has been widely used, despite the high manufacturing costs involved. As an alternative, a flexible solid metal seal offers not only sufficient tightness of the butterfly valve, meeting specification requirements, but also relatively low manufacturing costs. In this study, a design criterion to ensure the seat tightness of the butterfly valve using the flexible solid metal seal is proposed. The contact pressure can be calculated by the simulation of the frictional contact behavior between the surface of the metal seal and the valve disc. The geometry of the flexible solid metal seal is determined so that it satisfies the design criterion for sufficient seat tightness, and is verified by experiments according to BS6755 and BS6364.
한상욱(Sang Uk Han),안준태(Jun Tae Ahn),이경철(Kyung Chul Lee),한승호(Seung Ho Han) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.9
밸브는 지진하중 하에서 구조안전성이 요구되는 원자력 발전소 파이프 라인 시스템에 설치되는 중요한 장비 중 하나이다. 밸브의 성능향상을 위한 형상최적설계에서 지진하중조건을 고려한 밸브의 구조안전성 검증이 반드시 필요하다. 최근, 이론적인 내진검증 기법과 절차가 체계화되어 있어 지진하중하에서 설계조건을 만족하는 대상체의 적절한 설계변수가 이론적으로 얻어지고 있다. 본 연구에서는 원자력 발전소용 200A 버터플라이밸브를 대상으로 KEPIC MFA 에서 제시하고 있는 이론적인 정적내진해석과 동적내진해석 절차를 통하여 내진검증을 수치해석기법과 실험을 병행하여 수행하였다. 자중, 운전조건 및 안전정지지진하중 조건을 모두고려한 정적내진해석을 통해 밸브의 스템과 바디 접촉부에 작용하는 최대 작용응력이 135MPa 으로 도출되었다. 또한 동적내진해석시 적용한 응답스펙트럼 해석법과 모드조합법으로 계산된 최대응력은 183MPa 이었다. 이는 밸브 소재의 허용강도 대비 안전계수가 1.7 및 1.3 수준임을 확인하였다. Valves are one of the most important components of a pipeline system in a nuclear power plant, and it is important to ensure their structural safety under seismic loads. A crucial aspect of structural safety verification is the seismic qualification, and therefore, an optimal shape design and experimental seismic qualification is necessary in case the configuration of the valve parts needs to be modified and their performance needs to be improved. Recently, intensive numerical analyses have been performed before the experimental verification in order to determine the appropriate design variables that satisfy the performance requirements under seismic loads. In this study, static and dynamic numerical structural analyses of a 200A butterfly valve for a nuclear power plant were performed according to the KEPIC MFA. The result of static analysis considering an equivalent static load under SSE condition gave an applied stress of 135 MPa. In addition, the result of dynamic analysis gave an applied stress of 183 MPa, where the CQC method using response spectrums was taken into account. These values are under the allowable strength of the materials used for manufacturing the butterfly valve, and therefore, its structural safety satisfies the requirements of KEPIC MFA.