Modelamiento y análisis de esfuerzos en una unión soldada con defectologia para un tanque de almacenamiento de crudo en acero A-36 con método SMAW en una junta horizontal a tope en V

Abstract

The following thesis focused on a finite element simulation of a welding process using the SMAW method in a V-butt joint of A-36 steel applied to a crude oil storage tank using ANSYS software, where the aim was to predict the thermal behavior of the weld, the consequences of the process and the structural behavior of the model with its design factors. Initial calculations were performed to define parameters such as the thickness of the rings for the location of the joint, the working pressure and the projected diameter of the tank; some theoretical stresses present in the tank were calculated. Then, the two welded joints were modeled using the SolidWorks CAD software, made in order to have a conformity and non-conformity according to the international API 650 standard. These models were exported to the ANSYS software in its Workbench section. In the first stage of the simulation, the transient thermal process was executed, a stage in which the welding was replicated in its SMAW method and where the thermal behavior of the joints was obtained in an interval of 120 seconds. The second stage of the simulation consisted of the structural section, where conditions such as hydrostatic pressure, the force of the tank weight, among others, were considered. With this, deformation and stress results were obtained, influenced by the previous thermal development in the model. With the results of the simulation, several detail nodes were set at certain distances from the weld bead, at these points the thermal behavior was obtained and, based on the CCT diagram of the material, the cooling rates of each point were determined. Once the velocities were obtained, the phases present in the material and their respective percentage at each point in both the rejection and acceptance joints were calculated. In the structural part, points in the porosities of both joints were also determined, and the stresses and strains present in these nodes were analyzed. Finally, the thermal and structural results in the nodes of both joints were compared to evaluate which of the two models presents a better performance and efficiency under the conditions established for the storage tank. Once the development was completed, the respective analysis was carried out, in which it was emphasized that the value of the stresses and strains is influenced by the amount of porosities and their diameter, as well as the possible problems that this may mean over time for the possible application in reality.