Seliverstova I. Development of methods for calculating additional stresses in thin-walled pipes, caused by local defects of their shape

Object of research - the influence of cross-sectional geometry defects or imperfections of welds on the stress state of main and industrial pipelines. The aim of the study - engineering analytical and numerical methods for determining the stress state of pipeline elements in the presence of geometric defects, such as angular and axial misalignments of welds and dents. Research methods - analytical methods based on the defining equations of the theory of shells in elastic formulation to determine the local stress state of shells with shape imperfections. Numerical methods of analysis based on the finite element method to determine the stress distribution in the zones of stress concentration from the presence of defects in the shape of pipelines in the form of angular and axial mismatches of the weld and dents. Theoretical and practical results are to obtain analytical dependences that can be included in the regulations of the oil and gas industry to determine the local stresses of shape defects; development of analytical methods and numerical models that can be used in the calculation and analytical justification of safe operation of main gas pipelines with shape defects. Scientific innovation is to develop an analytical approach to determining local stress-strain state pipeline defective joints (angular, axial misalignment) and approach on the basis of equivalent loads, which are applied to the defect shape - dent arbitrary three-dimensional shape. The results of the research were used by the organization PJSC "PVI ZIT NAFTOGASBUDIZOLYATSIYA" in determining the technical condition of sections of main gas pipelines in places of temporary transport crossings during the reconstruction of roads of Ukraine. The visual physical content of the solutions and the use of dimensionless parameters from a practical point of view allow to improve the relevant piping standards in terms of determining additional (shell bending) stresses when assessing local defects in the shape of main pipelines.