This study presents, for the first time, the mechanical behavior of API 5L pipeline steels X42, X52, X60, X70, X80, and X100 with external and internal corrosion defects as well as a combination of both defects that has been named external–internal corrosion defects. The conventional methods to predict failure pressure in corroded pipes, such as B31G, RSTRENG-1, SHELL, DNV-99, PCORRC, and FITNET FFS, have also been discussed in this article. In addition, pipeline failure pressure has been estimated using the finite element method, considering that it is the best approach to calculate actual failure pressure. The external and internal corrosion defect investigated in this research manifests as a rectangular shape with spherical ends at the edges. When the external–internal corrosion defect appears, failure pressure data decrease dramatically because of severe damage. This is due to the decrease in the ligament (effective area) caused by the corrosion defect. To have a good estimation of the pipeline failure pressure with an external–internal corrosion defect, DNV-99 method can be used with acceptable certainty.

中文翻译：

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内外腐蚀缺陷深度对油气管道失效压力预测的有限元模型

本研究首次展示了具有外部和内部腐蚀缺陷以及两种缺陷组合的 API 5L 管线钢 X42、X52、X60、X70、X80 和 X100 的力学行为，这些缺陷被称为外部-内部腐蚀缺陷。本文还讨论了预测腐蚀管道失效压力的传统方法，例如 B31G、RSTRENG-1、SHELL、DNV-99、PCORRC 和 FITNET FFS。此外，考虑到它是计算实际失效压力的最佳方法，使用有限元方法估算了管道失效压力。本研究中研究的外部和内部腐蚀缺陷表现为边缘为球形端的矩形。当出现外-内腐蚀缺陷时，由于严重损坏，故障压力数据急剧下降。这是由于腐蚀缺陷导致韧带（有效面积）减少所致。为了更好地估计具有外部-内部腐蚀缺陷的管道故障压力，可以使用 DNV-99 方法并具有可接受的确定性。