Uma avaliação numérica de métodos semi-empíricos de cálculo de pressão de falha de dutos corroídos

Abstract

One of the most common modes of transport of the oil flow and its derivatives are the metal pipes. The main challenge of the pipeline network operators is to ensure the safety of the system with the maximization of its production capacity. Periodic inspections are essential to assessing pipeline integrity. Corrosion is one of the main problems that causes failures in pipeline structures. Semi-empirical analytical methods have been developed to calculate the rupture pressure of pipes subjected to external corrosion and are largely used due to its simplicity and speed. Numerical methods, particularly the Finite Element Method, have generated reliable results in relation to experimental tests and semi-empirical methods, besides allowing to evaluate more complex situations such as interactions between corrosion defects or combined loads, however, they are not largely employed as they require capable professionals and take a long time. This work aims to investigates the conservatism of the semi-empirical methods of calculation of failure pressure of pipelines with short corrosion defects by means of computational simulations. Numerical models are developed and compared with experimental tests to validate the simulations. A series of defects is modeled by varying the length of the defect and its depth. The physical and geometrical nonlinearity of the material is considered. It is noted that the results of the failure pressure obtained via the finite element method trend to approach the conservatism of the semi-empirical methods for any length and depth of the short corrosion defects. Each semi-empirical method presents a conservatism in function of the geometry of the corrosion defect.