Aging pipelines may experience some different types of flaws, such as crack and corrosion, which are serious concerns for pipeline integrity. Hybrid flaws such as crack-in-corrosion (CIC), can be challenging to model and understand. For instance, predicting the failure pressure using finite element method (FEM) is extremely difficult, therefore, the extended finite element method (XFEM) is introduced here. Compared to the conventional FEM, which requires extremely fine meshes and is impractical for modelling dynamic crack propagation, XFEM is computationally efficient as there is no need to update the mesh elements in order to track the crack path. This paper aims to study the mesh sensitivity of XFEM for predicting failure pressure of CIC defects and the effect of different CIC parameters on the failure pressure. ABAQUS v 6.14 was used for this simulation study. For simplicity, only half of the pipe was modelled assuming symmetry around the horizontal plane. A CIC defect was placed at the exterior of the pipe. The corroded area was assumed to be semi-elliptical, and the crack was simulated as a longitudinal crack. In this paper, the failure pressure was based on the crack reaching the last element. Several models were built in which the length and width of the elements at the crack tip were changed. The optimum mesh size was then found and was applied into several models with different crack depths, corroded area widths and corrosion patterns. The results showed that the failure pressure was reduced with increasing crack depth, while both corrode area width and corrosion pattern only have a secondary effect on the failure pressure.


Failure Pressure Prediction of Crack in Corrosion Defects in 2d by Using Xfem

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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