Influence of the Corrosion Anomaly Class on Predictive Accuracy of Burst Capacity Models for Corroded Pipelines
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(2020) 6:45
ORIGINAL PAPER
Influence of the Corrosion Anomaly Class on Predictive Accuracy of Burst Capacity Models for Corroded Pipelines J. Bao1 · W. Zhou1 Received: 24 July 2020 / Accepted: 22 September 2020 © Springer Nature Switzerland AG 2020
Abstract The present study investigates the impact of corrosion anomaly classes on the prediction accuracy of seven existing burst capacity models for corroded pipelines, namely B31G, B31G-M, Shell92, PCORRC, PCORRC-M, CSA and RSTRENG, based on 897 corrosion anomalies on 16 naturally corroded pipe specimens removed from in-service pipelines. The 897 corrosion anomalies are classified into seven classes, namely pin hole, axial slotting, axial grooving, circumferential slotting, circumferential grooving, pitting and general corrosion, based on the pipeline operators forum (POF) anomaly classification system. The seven burst capacity models and finite element analyses (FEA) are employed to evaluate the burst capacities of the corrosion anomalies. The accuracies of the burst capacity models are assessed and compared based on the FEA-to-model predicted burst capacity ratios for different classes of anomalies. The results suggest that the PCORRC model is suitable for the non-general classes of corrosion anomalies, whereas the CSA model is recommended for the general corrosion class of anomalies. Keywords Corroded pipeline · Finite element analysis · Corrosion anomaly classification · Burst capacity model
Introduction Metal loss corrosion is one of the major threats to the integrity of buried oil and gas pipelines [1]. Corrosion on buried pipelines is largely influenced by properties of the surrounding soils such as the pH value, soil resistivity, water content and dissolved chloride. Extensive research has been reported in the literature to predict the severity of corrosion on pipeline using soil parameters as predictors [2–4]. In practice, pipeline engineers carry out the fitness-for-service (FFS) assessment to evaluate the structural integrity of corroded pipelines and then determine necessary, if any, mitigation actions. The FFS assessment of a corroded pipeline generally involves evaluating the pressure containment capacity, i.e. burst capacity, of the pipeline using one of several widely accepted semi-empirical burst capacity models such as ASME B31G [5], B31G Modified [6] and RSTRENG [6] models. It follows that the predictive accuracy of the burst capacity model is critically important for the FFS * W. Zhou [email protected] 1
Department of Civil and Environmental Engineering, The University of Western Ontario, London N6A 5B9, Canada
assessment and subsequent decision-making for corrosion mitigations [7, 8]. The accuracy of burst capacity models is commonly evaluated by comparing the burst capacities observed from a series of full-scale burst tests (Ptest) of corroded pipe segments with the corresponding capacities predicted by the models. Benjamin et al. [9, 10] investigated the accuracy of the B31G, B31G Modified, RSTRENG and DNV [11] models based on full-sca
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