The block element method is used to study the behavior of a coated material under the assumption that the surface is exposed to a corrosive liquid medium that can destroy the coating. It is assumed that the destruction begins with the formation of vertical local cracks in the coating, which then grow and lead to the exposure of the unprotected surface. Assuming the possibility of modeling a liquid layer by shallow water equations, the block structure including a body in the form of a deformable layer, a defective coating modeled by Kirchhoff plates and a heavy liquid layer is investigated. The distribution of stress concentration in such a block structure is studied. The analysis showed that even in the presence of a liquid, the features of the stress-strain state of the material inherent in the case of its absence are preserved. The conditions both allowing further use of such object and excluding this possibility are revealed.