Liquefied natural gas tank analysis: cryogenic temperatures and seismic loading

Abstract

This paper describes several of the advanced non-linear finite-element analyses required for the design of a full containment 155 000 m3 liquefied natural gas (LNG) tank. The focus is on the analysis of the prestressed concrete outer containment, which resists the loading of cryogenic liquid in the case of inner tank failure. Accurate modelling of the effects of −164°C LNG on a concrete tank is in itself a significant non-linear task. Of critical importance are the stresses and cracking induced in the wall by the evolution of a cold front. A transient analysis is presented that ensures the tank remains liquid-tight. The tank is also required to remain liquid-tight in a seismic event, which in this case follows inner tank failure. A transient dynamic analysis of earthquake loading on a tank containing the cryogenic liquid is also presented. The work, carried out using Diana and Ansys, fully confirms the adequacy of the design.