Stress distribution and fracture pattern analysis of spherical LNG storage tank dome caused by thermal load

Abstract

In large-scale LNG storage tanks, the temperature difference between the inner and outer surfaces of tank dome causes substantial thermal stress, which significantly affects crack development and stress distribution in the dome. Conventional calculation method for thermal stress distribution in spherical shell structure is complex. In this study, a stress superposition method is proposed for approximate calculation of stress distribution in tank dome, in order to obtain a simple formula for guiding the design and analysis of practical projects. A comparison analysis shows that the approximate calculation method yields close results as numerical simulation, thereby can be used for practical projects. Further analysis shows that when being in contact with low-temperature volatile natural gas, the tank dome generates excessive thermal stress, leading to uniform distribution of meridian cracks along the circumferential direction. The meridian cracks first occur on the inner surface of the dome edge and then rapidly spread towards the center and outer surface, ultimately penetrating the entire tank dome.