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In this work, failure prediction of corroded pipelines under combined loads of internal pressure and axial compressive force is investigated through the Finite Element Method. The study was carried out using the PIPEFLAW program, which was specially developed to automatically generate and analyze corroded pipelines models. Two configurations of idealized defects in pipeline were investigated: with two and three rectangular defects. This work was divided into two stages where, on the first stage, the analysis is performed considering only internal pressure. On the second stage, combined loads are simulated considering internal pressure and axial compressive forces. Results show that failure pressure values decrease with the increase in the axial compressive force, for both Finite Elements models analyzed.

In order to improve the assessment of the hydrostatic collapse of deepwater pipelines a new method named, RCA (Renewed Classical Approach) method, was developed. The development of this method, which is a modified version of the DNV method, was based on the results of several nonlinear Finite Element (FE) analyses. In this paper the development of the RCA method is presented. Initially an overview of the classical approach is presented. Then two assessment methods are presented (the DNV method and the RCA method) and the FE modeling is described. Finally the collapse pressures predicted by the assessment methods are compared with those predicted by the FE models.

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