• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.17-23
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• 2021

The membrane-type Liquefied Natural Gas (LNG) cargo tank is equipped with a double barrier to seal the LNG, of which the secondary barrier serves to prevent LNG leakage and mainly uses fiber-reinforced composite materials. However, the composite materials have thermal expansion anisotropy, which deteriorates shape distortion and mechanical performance due to repeated thermal loads caused by temperature changes between cryogenic and ambient during the unloading of LNG. Therefore, in this study, the longitudinal thermal expansion characteristics of the composite materials were obtained using a vertical thermo-mechanical analyzer, and the elastic modulus was obtained through the tensile test for each temperature to perform thermal load analysis for each direction. This is considered that it is useful to secure reliability from the viewpoint of the design of materials for a LNG cargo hold.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.1
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• pp.207-212
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• 2024

Recently, with the strengthening of environmental regulations, there has been an increasing interest in eco-friendly energy sources, leading to a trend of the increasing scale of Cargo Containment Systems (CCS) for Liquefied Natural Gas (LNG) carriers. Among these systems, membrane tanks have gained popularity in LNG transport vessels due to their superior spatial utilization and competitiveness. However, due to high initial investment costs and the difficulty in repair in case of damage, a safety layer, the secondary barrier, must be installed without fail. In this study, in order to apply a new secondary barrier to the existing membrane-type LNG CCS, tests were conducted on the fiberglass layer previously used in the Triplex-Flexible Secondary Barrier (FSB), substituting it with basalt fiber. Tensile and vertical tensile tests were performed to assess the newly applied material. Environmental tests were conducted at room temperature (25℃) and extremely low temperatures (-170℃), considering the temperatures to which substances may be exposed during LNG vessel operations. The basalt-FSB produced in this study demonstrated superior results compared to the specifications of the existing product, confirming its potential applicability for implementation.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.6-17
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• 2009

The present paper addresses development of a GTT NO96 membrane type 170K m3 LNG carrier targeted to operate in moderate ice infested seas including Baltic Sea, Sakhalin port of Sea of Okhotsk, Murmansk port of Barents Sea, etc. Critical design issues are covered in detail to meet the requirements coming from the missioned operation conditions comprising low design ambient temperature, harsh wave conditions, stringent environmental protection policies, etc.

• Journal of Welding and Joining
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• v.13 no.3
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• pp.1-7
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• 1995

1992년 9월 현재 전 세계적으로 운전 중(건설포함)인 액화 및 인수기지의 LNG 저장탱크는 지상식-이중벽 금속 탱크, 지상식-맴브레인 PC 탱크, 지상식-자립식 내부탱크/PC 외부탱크, 피드식-RC(Reinforced Concrete) 보강둑 탱크, 피트식-이중벽 금속탱크, 피트식-자립식 내부탱크/PC 외부탱크 및 지하식 탱크의 7가지 유형으로 나 타낼 수 있다. 또한 액화천연가스를 저장하는 내부탱크 소재에 따라 9%Ni강 및 MEMBRANE(SUS304) 형식으로 대별할 수 있다. MEMBRANE 저장탱크 형식의 핵심기술인 MEMBRANE은 -162.deg.C의 LNG에 의한 열수축팽창에 견딜 수 있도록 스테인레스강판 (SUS304)을 사용하여 기하학적으로 특이한 주름진 형상을 갖도록 설계되었으며 주름 형상에 따라 프랑스의 테크니가즈(Technigaz), 일본의 가와사끼(Kawasaki). 미쓰비시 (Mitsubishi), 이시가와지마하리마(Ishikawajima-Harima)사의 멤브레인과 세계에서 3번째로 한국가스공사 연구개발원이 개발한 링디식 멤브레인으로 구별할 수 있다. 본 해설에서는 국내의 전국 천연가스 공급사업계획 및 건설현황을 검토하고 최근 전 세계적으로 널리 사용되고 있는 액화천연가스 저장탱크의 종류를 용량별, 년도별로 분석하여 전세계의 액화천연가스 저장탱크에 관해 소개 하겠다.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.9-14
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• 2016

STS304L of membrane structure has been used for a LNG storage tank and has exposed long time under the cryogenic temperature. The purposes of this study are to evaluate the mechanical properties of base and used materials for STS304L of membrane. The tensile and high cycle fatigue tests were investigated for STS304L of membrane used over 20 years at room temperature and $-162^{\circ}C$. In addition, the test of base STS304L was performed in order to compare with used material properties. The chemical composition and phase change were investigated from EDS and XRD. From results of tensile test, yield and ultimate tensile strengths of used STS304L are smaller than those of base STS304L. S-N curves were obtained from fatigue tests at both temperatures. Also, P-S-N curves were presented with statistical method recommend by JSME-S002. Fractography was conducted for analysis of fracture mechanisms.

• Journal of Hydrogen and New Energy
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• v.35 no.1
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• pp.90-96
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• 2024

In this paper, a new technology to obtain electronic grade, highly pure carbon dioxide by using membrane and liquefied natural gas (LNG) cold heat assisted cryogenic distillation has been proposed. PRO/II with PROVISION release 2023.1 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function to predict pure component vapor pressure versus temperature more accurately was selected for the modeling of the membrane and cryogenic distillation process. Advantage of using membrane separation instead of selecting absorber-stripper configuration for the concentration of carbon dioxide was the reduction of carbon dioxide capture cost.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.710-717
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• 2000

Tensile and fracture toughness tests of the cold-rolled STS 304 steel plate for membrane material of LNG storage tank were performed at wide range of temperatures, 11 IK(boiling point of LNG), 153K , 193K and 293K(room temperature). Tensile strength significantly increases with a decrease in temperature, but the yield strength is relatively insensitive to temperature. Elongation at 193K abruptly decreases by 50% of that at 293K, and then decreases slightly in the temperature range of 193K to 111K. Strain hardening exponents at low temperatures are about four times as high as that at 293K. Elastic-plastic fracture toughness($J_c$) and tearing modulus($T_{mat}$) tend to decrease with a decrease in temperature. The $J_c$ values are inversely related to effective yield strength in the temperature range of 111K to 293K. These phenomena result from a significant increase in the amount of transformed martensite in low temperature regions.

• Journal of Ocean Engineering and Technology
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• v.12 no.1
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• pp.50-57
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• 1998

The leak before break(LBB) concept is generalized on the design of LNG tanks, pressure vessels and nuclear reactor in that any leakage of containment, in whatever amount, will not result in catastropic failure. For this purpose it is necessary to determine the surface crack shape, the opening displacement and the risk of catastropic brittle fracture when it becomes a through crack. In this study the crack propagation behavior of surface flaws and the crack opening displacement of through cracks under combined membrane and bending stresses were investigated with fatigue tests and fracture toughness test of aluminium alloy A5083-O. And fracture mechanics analysis of the crack opening displacement of through cracks were made in order to develop a new model expressing the behaviors of COD under combined membrane and bending stresses.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1192-1200
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• 2008

This paper is concerned with the thermal design of the $138,000m^3$ class membrane type LNGC. To predict the temperature distribution, BOG and BOR, 3-dimensional numerical calculation was carried-out for the quarter of No.3 LNG tank. These sequence analyses were performed under the standard conditions of IMO ship design condition, USCG ship design condition and the Korean flag LNGC's route condition according to the 6-voyage modes. As the results, temperature behavior, heat flux, total penetrating heat, BOG and BOR were obtained, and those were compared with the maneuvering results considering the real temperature variation of air and sea water temperature at noon time. For securing the safety of LNGC during the ballast voyage, optimum control patterns of pressure and temperature in LNG tank is suggested in this paper.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.96-102
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• 2008

As LNG tank is operated around $-162^{\circ}C$, an experimental approach on the cryogenic temperature tensile and fatigue strengths of SUS304L lap joint weld is very important at the design stage of membrane type LNG tank. In this study, in order to estimate the tensile and fatigue strengths of SUS304L lap joint weld at cryogenic temperature condition, tensile and fatigue tests were conducted. Also, S-N curves are presented with statistical testing method recommended by JSME. As a result of the experimental approach, the d￡sign guide of fatigue strength is proposed and that is expected to be useful for membrane type LNG tank design.