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A Comprehensive Empirical Evaluation of Probabilistic Corrosion Growth Rate Models

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Traditional Corrosion Growth Rate (CGR) models used in the integrity assessment of corroded pipelines are deterministic. A common Magnetic Flux Leakage (MFL) inline inspection (ILI) tool performance specification on general corrosion anomaly depth is +/- 10% Wall Thickeness (WT) at 80% confidence which corresponds to a standard deviation of 7.81% WT.  Probabilistic Corrosion Growth Rate (PCGR) models incorporate these large measurement uncertainties and provide more realistic reliability assessments

Product Number: 51323-18883-SG
Author: Gabriel Langlois-Rahme, Mahmoud Ibrahim, Miaad Safari, Yanping Li, Chike Okoloekwe
Publication Date: 2023
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Probabilistic Corrosion Growth Rate (PCGR) models are typically studied on one or two Inline Inspections (ILIs) of a small sample size and use evaluation metrics that are operator specific. This comprehensive empirical assessment aims to expand the evaluation of PCGR models by examining anomalies that had distinct Box-to-Box (B2B) matches in four successive ILIs, resulting in 57,678 individual external corrosion anomalies from twelve pipelines of differing products, vintages, coatings, material specifications, and operating environments. This paper evaluates several PCGR models which are a combination of well-known industry models and simulation-based regression techniques. These models were evaluated using a historical train-test split on each studied anomaly set, where three prior ILIs were used to simulate the depth of each anomaly projected to the year of the fourth ILI. The simulated depths were compared to the measured depths of the final ILI. Statistical metrics and graphical techniques were used to measure a model’s predictive ability to effectively simulate the mean depth and uncertainty. The models presented in this paper are starting points for oil and gas transmission pipeline operators with ILI data to model corrosion growth with time. This work provides empirical guidance on how to use multiple corrosion ILI B2B matches to predict corrosion depth growth.

Probabilistic Corrosion Growth Rate (PCGR) models are typically studied on one or two Inline Inspections (ILIs) of a small sample size and use evaluation metrics that are operator specific. This comprehensive empirical assessment aims to expand the evaluation of PCGR models by examining anomalies that had distinct Box-to-Box (B2B) matches in four successive ILIs, resulting in 57,678 individual external corrosion anomalies from twelve pipelines of differing products, vintages, coatings, material specifications, and operating environments. This paper evaluates several PCGR models which are a combination of well-known industry models and simulation-based regression techniques. These models were evaluated using a historical train-test split on each studied anomaly set, where three prior ILIs were used to simulate the depth of each anomaly projected to the year of the fourth ILI. The simulated depths were compared to the measured depths of the final ILI. Statistical metrics and graphical techniques were used to measure a model’s predictive ability to effectively simulate the mean depth and uncertainty. The models presented in this paper are starting points for oil and gas transmission pipeline operators with ILI data to model corrosion growth with time. This work provides empirical guidance on how to use multiple corrosion ILI B2B matches to predict corrosion depth growth.

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Product Number: 51320-14640-SG
Author: Joseph Mazzella, Thomas Hayden, Haralampos Tsaprailis, Len Krissa
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50 mV As a Screening Criteria for Shorted Casings – Case Study

Product Number: 51323-18899-SG
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Publication Date: 2023
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While performing cathodic protection surveys, carrier pipe and casing potential readings are typically recorded at the same test station location near the end of a casing. Comparing these potentials should reveal a difference between the cathodically protected pipe versus an unprotected and electrically isolated casing. The difference in potentials is one of available tests to determine whether a casing may be electrically shorted to the carrier pipe. The pipe-to-electrolyte and casing-to-electrolyte potential comparison is usually the initial “screening” method.
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51317--9504-Validation of Corrosion Growth Rate Models

Product Number: 51317--9504-SG
ISBN: 9504 2017 CP
Author: Yan Ping Li
Publication Date: 2017
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Validation results of feature level and joint level CGR based on feature matching and signal matching. These results enable pipeline operators to establish defect repair schedules and re-inspection intervals with increased confidence.
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