Justification of the estimation technique for the technical condition of the tank with inadmissible imperfections in the wall shape

Abstract

The paper has its focus on the problem of estimating the stress-strain state of the vertical steel tanks with the inadmissible geometric imperfections in the wall shape. In the paper, the authors refer to an actual tank to demonstrate that the use of certain design schemes can lead to the raw errors and, accordingly, to the unreliable results. Obviously, these design schemes cannot be based on when choosing the real repair technologies. For that reason, authors performed the calculations of the tank removed out of service for the repair, basing on the developed finite-element model of the VST-5000 tank with a conical roof. The proposed approach was developed for the analysis of the SSS (stress-strain state) of a tank having geometric imperfections of the wall shape. Based on the work results, the following was proposed: to amend the Annex A methodology “Method for calculating the stress-strain state of the tank wall during repair by lifting the tank and replacing the wall metal structures” by inserting the requirement to compulsory consider the actual stiffness of the VST entire structure and its roof when calculating the structure stress-strain state.