PREDICTING THE FAILURE PRESSURE OF PIPELINES CONTAINING NONUNIFORM DEPTH CORROSION DEFECTS USING THE FINITE ELEMENT METHOD

摘要

PETROBRAS is conducting a research project with the purpose of investigating the behavior of pipelines containing long nonuniform depth corrosion defects. In the first phase of this project, burst tests of two tubular specimens were carried out. Each of the two specimens had one external nonuniform depth corrosion defect, machined using spark erosion. This defect consists of two short and deep defects within a long and shallow corrosion patch, longitudinally oriented. The second phase of the project aims at appraising the performance of two different finite element models: a shell model and a solid model. This paper describes the application of these models in the analysis of the two tubular specimens containing a long nonuniform depth defect that were tested in the first phase of this project. The failure pressures predicted by the two types of FE models are compared with the burst pressures measured in the laboratory tests. Also a comparison between the results obtained by these models is presented. It is concluded that the solid model is more accurate than the shell model, but both models proved to be capable of simulating the failure behavior of defects constituted by a long and shallow corrosion patch with deep defects over it.