INFLUENCE ANALYSIS OF DESIGN SOLUTIONS OF UNDERGROUND PIPELINES CURVED SECTIONS ON THEIR STRESS-STRAIN STATE

Abstract

Background Underground pipelines of main oil and gas pipelines are being built in all climatic and geographical zones of the country. A significant part of the main oil and gas pipelines are laid in flat-hilly and mountainous terrain. In hilly and mountainous areas, pipelines are laid in a trench with a vertical turn. During the operation of oil and gas main pipelines, longitudinal compressive forces arise under the influence of a positive temperature difference and operating pressure. These forces lead to longitudinal and transverse movements of the underground pipeline in convex sections of the turn in the vertical plane. When the underground pipeline moves in the longitudinal and transverse directions, additional bending stresses arise. At the same time, a decrease in longitudinal compressive forces occurs, which leads to a decrease in the values of longitudinal compressive stresses. In accordance with the requirements of SP 36.13330.2012 «Trunk Pipelines», the maximum total longitudinal stresses acting in the pipe wall should be determined from all (taking into account their combination) standard loads and actions, taking into account the longitudinal and transverse displacements of the pipeline. At the same time, the longitudinal and transverse movements of the pipeline and the resulting stresses due to these movements depend on the design solutions for underground pipeline laying. Aims and Objectives Ensuring the strength of pipes and the safe operation of oil and gas pipelines based on the improvement of calculation methods and design of curved sections of underground pipelines. Results The assessment of the level of the maximal longitudinal stresses in the underground pipeline is carried out for various design solutions of the angle of rotation on convex areas of the terrain. Technical solutions to ensure the strength of pipes for oil and gas trunk pipelines have been proposed.