Design of the integrated structure system for the pipeline and maintenance ladder inside LNG storage tank

The split-type design and installation method for the pipeline and maintenance ladder inside conventional LNG storage tanks is disadvantageous with complicated construction and high cost, and the leakage risk of the main tank of the tank(i.e., inner tank)is greatly increased due to the welding disturbance.In this paper, the structure of LNG inner tank was analyzed comprehensively and then a set of design proposal for the integrated structure of the pipeline and maintenance ladder inside LNG storage tank was put forward.In this proposal, the pipeline is taken as a load carrying component, the lateral joints and the maintenance ladder are taken as fixed components, and they support each other to form a selfsupporting structure system independent of the inner tank wall.Then, based on the typical extreme conditions in the design of the LNG tank, the integrated structure system was calculated and analyzed by means of numerical simulation analysis method.Finally, the safety and reliability of the integrated structure system was verified by means of allowable stress method.It is indicated that this system is not only able to achieve the functional requirements of the pipelines and maintenance ladder, but also independent of the side support of the inner tank wall.In this way, a self-supporting stable structure system is established and it can effectively improve the economy, safety and reliability of tank construction.The research results can provide the theoretical guidance for the design and safety reliability analysis of the integrated structure system inside LNG tanks.