Population-based approach to estimate corrosion growth in pipelines Dann, Markus R.; Maes, Marc A.
Corrosion in pipelines can lead to leak and rupture failures with significant consequences for people, the economy, and the environment. Corrosion growth rates are often determined from the results of in-line inspections. Detected corrosion anomalies from at least two inspections are matched with respect to their location in the pipeline and the measured growth path is used to infer current and future corrosion growth. Reliable defect matching is essential to infer credible corrosion rates for pipeline integrity assessments. If high-density corrosion is present, as frequently observed in upstream and subsea pipelines, reliable matching can typically be performed for a limited number of features. The remaining unmatched elements are usually removed from the corrosion growth analysis. The objective of this paper is to introduce a population-based corrosion growth analysis that neither requires matched defects nor removes corrosion anomalies from the analysis. All reported corrosion anomalies from an inspection are considered as a single population and the probabilistic approach determines the corrosion growth of two given populations. Adjustments are included for sizing, detectability, and false call uncertainties to determine the underlying true corrosion growth process. The results are used to estimate future corrosion evolution in joints and entire pipeline segments for informed deterministic or reliability-based integrity assessments of pipelines. The major advantage of this new approach is that the model can easily process mass pipeline inspection data.
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