Objective Through reducing the total mass of the main container of LNG film tank, the development and market expansion of LNG storage facilities are promoted.

Methods The basic geometric parameters of the main container of the film tank are designed, and the mathematical model of the tank and the required objective function are established. The stress of the tank in the full tank state is analyzed and calculated, and the basic geometric data is parameterized and the thickness of the tank wall is optimized by ANSYS software. The mathematical model of the dome is solved by using particle swarm optimization algorithm and MATLAB software programming.

Results The optimal curvature radius of the dome is 28 000 mm, the minimum thickness of the tank wall is reduced by 0.50 mm, the total mass of the tank roof is reduced by 103 t, and the maximum thickness of the tank wall is reduced by 0.62 mm.

Conclusions The optimized calculation results are qualified after the air pressure test, which has important reference value for the lightweight research and cost reduction of LNG film tank.