STUDY OF THE WALL RIGIDITY OF A VERTICAL CYLINDRICAL STEEL TANK DURING ITS INSTALLATION BY THE SPIRAL-WOUND METHOD

Abstract

The paper presents the results of a study of the influence of the wall diameter of a vertical cylindrical steel tank designed for storing petroleum products on its stiffness characteristics and the applicability (for the manu-facture of this wall) of the spiral-winding metod, according to which the tank wall is made of rolled sheet metal, during the unwinding of which a wall is formed in the form of a spiral, ad-jacent turns of which are continuously connected by a welded seam, forming a sealed shell.To solve the problem, a finite element analysis of the tank wall was performed, within which the wind load was taken as the calculated one, due to which the greatest lateral deformations of the tank wall during its construction are possible, which can cause disruption of the technological process of its construction using spiral-winding method.The paper considers tank wall solutions of different diameters (in the range from 10 to 65 m), which have the smallest wall thicknesses adopted in accordance with the recommendations from the Russian standard.Modeling of the tank wall included the preparation of geometric and calculation models. The geometric model is presented in the form of an axisymmetric cylindrical shell, on the outside of which flat ribs are placed at a constant pitch along the shell axis, giving it additional stiffness. The calculation model includes a geometric model of the wall, to which a wind load is applied from the outside, the pressure from which on the tank wall is constant along its height; it is maximum under normal action and decreases to zero under tangential action. Using the calculation model, firstly, a dependence was obtained that reflects the effect of a change in the height of the tank wall on the maximum radial displacements in its base near the supports, and, secondly, the dependence of the maximum radial displacements of the tank wall in its base near the supports, depending on its diameter.The results of the analysis, in particular, showed that the stiffness of the wall obtained on the basis of the spiral-winding method practically does not change with an increase in its diameter (and a corresponding increase in thickness).