This article is containing results of strength calculation for a large air filter structure consisting out of a set, assembled into pyramid, cylindrical fiberglass tanks. Inside an each tank is fixed filter element. The tanks are connected by pipes so that the polluted air is entering the first tank is going further throw all another tanks and is purifying by filters are located in them. The construction is static and the stress states in walls of each particular tank is forming by the deadweight of the tank, as well as, by the weight of the tanks are located above this tank in the structure. Two approaches were executed. First – all structure (according symmetry conditions one forth part of the structure was observed) stress state was simulated using FEM software SolidWorks. Second- contact interaction forces between tanks in the structure were calculated using MathCad software under rigid interaction assumption. More heavily loaded tanks were numerically investigated (using fine FEM mesh). The model and the calculated deformed states were carefully analyzed. Acceptable tank’s wall thickness corresponding to lads existing in the structure was obtained.