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Structural safety assessment for FLNG-LNGC system during offloading operation scenario

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Abstract

The crashworthiness of the cargo containment systems (CCSs) of a floating liquid natural gas (FLNG) and the side structures in side-by-side offloading operations scenario are studied in this paper. An FLNG vessel is exposed to potential threats from collisions with a liquid natural gas carrier (LNGC) during the offloading operations, which has been confirmed by a model test of FLNG-LNGC side-by-side offloading operations. A nonlinear finite element code LS-DYNA is used to simulate the collision scenarios during the offloading operations. Finite element models of an FLNG vessel and an LNGC are established for the purpose of this study, including a detailed LNG cargo containment system in the FLNG side model. Based on the parameters obtained from the model test and potential dangerous accidents, typical collision scenarios are defined to conduct a comprehensive study. To evaluate the safety of the FLNG vessel, a limit state is proposed based on the structural responses of the LNG CCS. The different characteristics of the structural responses for the primary structural components, energy dissipation and collision forces are obtained for various scenarios. Deformation of the inner hull is found to have a great effect on the responses of the LNG CCS, with approximately 160 mm deformation corresponding to the limit state. Densely arranged web frames can absorb over 35% of the collision energy and be proved to greatly enhance the crashworthiness of the FLNG side structures.

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Authors and Affiliations

  1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin, 300072, China

    Zhi-qiang Hu

  2. State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China

    Zhi-qiang Hu, Dong-wei Zhang & Dong-ya Zhao

  3. Marine Design & Research Institute of China, Shanghai, 200240, China

    Gang Chen

  4. Nantong COSCO KHI Ship Engineering Co. Ltd, Nantong, 226005, China

    Dong-wei Zhang

Authors
  1. Zhi-qiang Hu
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  2. Dong-wei Zhang
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  3. Dong-ya Zhao
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  4. Gang Chen
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Corresponding author

Correspondence to Zhi-qiang Hu.

Additional information

Foundation item: This work was financially supported by the State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University (Grant No. HESS-1404), and the National Natural Science Foundation of China (Grant No. 51239007).

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Hu, Zq., Zhang, Dw., Zhao, Dy. et al. Structural safety assessment for FLNG-LNGC system during offloading operation scenario. China Ocean Eng 31, 192–201 (2017). https://doi.org/10.1007/s13344-017-0023-4

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  • DOI: https://doi.org/10.1007/s13344-017-0023-4

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