Modeling of pipeline corrosion degradation mechanism with a Lévy Process based on ILI (In-Line) inspections

International audienceIn pipelines, one of the primary testing procedures used to identify the e↵ects and evolution of corrosion over time is through In-Line Inspections (ILI). ILI inspections provide detailed information regarding the inner and outer pipeline condition based on the remaining wall thickness. Based on this information, di↵erent approaches have been proposed to predict the degradation extent of the defects detected. However, these predictions are subject of uncertainties due to the inspection tool and the degradation process that poses some challenges for assessing an entire pipeline within the timespan between two inspections. To address this problem, ILI data was used to formulate a degradation model for steel-pipe degradation based on a Mixed Lévy Process. The model combines a Gamma and Compound Poisson Processes aimed for a better description of the degradation reported by the ILI data. The model seeks to estimate corrosion lifetime distribution and the mean time to failure (MTTF) more accurately. The model was tested on an actual segment of an oil pipeline, and the results have been used to support a preventive maintenance program

The lévy-based framework for deterioration modeling, reliability estimation and maintenance of engineered systems

Esta tesis presenta un marco conceptual, analítico y numérico para el modelado del deterioro de sistemas de ingeniería, orientado a la evaluación de la confiabilidad y de políticas óptimas de mantenimiento. El llamado "marco basado en Lévy" está formalmente desarrollado en la teoría de los procesos de Lévy y Lévy No-Homogéneos (NH Lévy). El marco surge de la necesidad de modelos estocásticos para estos sistemas, que describan situaciones complejas de ingeniería, tales como el efecto de múltiples fuentes de deterioro, con el fin de obtener de forma precisa y eficiente la confiabilidad y la evaluación de políticas óptimas de mantenimiento. En concreto, el marco desarrolla tres modelos de deterioro con complejidad creciente: el modelo de deterioro Lévy, NH Lévy, y NH Lévy Generalizado. Se proporcionan métodos analíticos y numéricos para el análisis de confiabilidad y la simulación de trayectorias, y para encontrar la edad óptima de reemplazo para sistemas con deterioro Lévy o NH Lévy. Estos métodos son precisos y computacionalmente eficientesThis thesis presents a conceptual, analytical and numerical framework for modeling deterioration of engineered systems oriented to the evaluation of reliability and optimal maintenance policies, referred to as the Levy-based framework. The framework is formally supported on the Lévy process and the Non-Homogeneous (NH) Lévy process. The framework arises from the need of stochastic models for deteriorating systems that describe complex engineering situations, such as the effect of multiple sources of degradation, to perform accurate and efficient time-dependent reliability analysis and the evaluation of optimal maintenance policies. Specifically, the framework develops three deterioration models with increasing complexity: the Levy, the NH Lévy, and the Generalized NH Levy deterioration models. Analytical and numerical methods are provided for reliability analysis and sample paths simulation, and for finding the optimal age-replacement maintenance policy for systems with Lévy or NH Lévy deterioration. These methods are accurate and computationally efficientDoctor en IngenieríaDoctorad

A unified formalism for modeling and reliability estimation of degrading systems

We present a framework to model degradation on deteriorating systems, and to find easy-to- evaluate expressions for important reliability quantities. The model allows to combine multiple degradation mechanisms in the form of shock-based degradation with arbitrary shock sizes and progressive degradation (as deterministic drift plus a gamma process, among others). In addition, the proposed approach can be used to obtain expressions for the reliability function, the mean and n-moments of the deterioration process Xᵼ, and the probability density and moments of the lifetime L. In this paper we also present a novel numerical method to compute these expressions, which is highly efficient and accurate. Furthermore, several deterioration models are compared in terms of the calculated reliability quantities, and the feasible moments of the deterioration Xᵼ. The results demonstrate the generality, versatility, efficiency and accuracy of the proposed framework, which can open a new productive research field in the area of probabilistic degradation models.Non UBCUnreviewedThis collection contains the proceedings of ICASP12, the 12th International Conference on Applications of Statistics and Probability in Civil Engineering held in Vancouver, Canada on July 12-15, 2015. Abstracts were peer-reviewed and authors of accepted abstracts were invited to submit full papers. Also full papers were peer reviewed. The editor for this collection is Professor Terje Haukaas, Department of Civil Engineering, UBC Vancouver.Facult