Reliability analysis of ovalized deep-water pipelines with corrosion defects. (May 2021)

• Record Type: Journal Article
• Authors: Motta, Renato de S.; Leal, Caroline F.; Ferreira, Adriano D.; Afonso, Silvana M.B.; Lyra, Paulo R.M.; Willmersdorf, Ramiro B.
• Is Part Of: Marine structures. Volume 77(2021)
• Publication Date: 2021-05
• Subjects: Corroded pipeline -- Ovalization -- Finite element modelling -- Nonlinear analysis -- Collapse pressure -- Structural reliability; Naval architecture -- Periodicals; Offshore structures -- Periodicals; Architecture navale -- Périodiques; Structures offshore -- Périodiques; Naval architecture; Offshore structures; Periodicals; 620.4162
• DOI: 10.1016/j.marstruc.2021.102969
• Languages: English
• ISSNs: 0951-8339

Abstract

Abstract: The accurate assessment of the remaining strength of corroded pipes is a subject that has been increasingly investigated over the past decades. This is because of the risk of significant social, economic, and environmental effects that may be caused by an accident. The finite element method has been successfully used to predict the collapse pressure considering external load. It was also used in this study. The literature primarily focused on the corroded pipes subjected to internal pressure. In this study, the out-of-roundness (ovalization) of the pipe was considered to evaluate the collapse pressure. Uncertainties should be incorporated into a computational model to assess the reliability of corroded pipes. Three methods for evaluation of the probability of failure were used: the first-order reliability method (FORM), traditional Monte Carlo (MC), and a new proposed methodology that combines MC results with the kernel density estimation method (MCkde). The probability of failure of ovalized corroded pipes subject to external pressure was computed. The results exhibited a good agreement between FORM and MCkde method. The statistical importance of each random variable was observed and the results were compared with those from intact ovalized pipes. The computation cost of the MC method with numerical simulation limits its use to the application under study. Solutions using the FORM and MCkde methods exhibited good agreement with those of the full MC method. However, the computational effort of the latter was independent of the stochastic dimension, and it was a derivative-free method. As expected, in general, the solutions based on empirical methods were conservative. Highlights: An accurate assessment procedure to compute the reliability of offshore corroded pipes is provided. FEM is an important way to obtain collapse pressure of ovalized corroded pipe (OCP). An automatic computational tool to the reliability analysis of OCP via FEM was developed. Ovalization uncertainty is an important parameter on reliability analysis of OCP. The proposed MCkde method is a more efficient variant of the original Monte Carlo method.