Abstract
Structural integrity and risk management have a wide interest because of its practical applications, such as oil and gas pipelines, piping systems under pressure in power stations, urban water, and heating networks. The main goal of this paper is twofold. Firstly, to estimate the unsteady pressureflow variations in a gas transmission grid within the framework of sequential data assimilation. This technique enables to determine accurately the maximum pressure at the localized defect on the pipeline by merging measurements that contain random errors into the inexact numerical flow model. For this purpose, a particle filter is used. The semi-discretization approach is applied to convert the nonisothermal flow model into an initial value problem of ordinary differential equations. The spatial discretization is based on a five-point, fourth-order finite difference approximation and the time marching was done using a diagonally implicit Runge-Kutta scheme. Secondly, to study the strength of steel tubes reinforced with composite sleeves containing localized part-wall thickness losses caused by corrosion while taking into consideration a safe operating pressure. For a steel thin-walled cylinder containing a wrap of fiberglass with epoxy resin, the burst pressure and sleeve thickness are determined. Finally, the repaired pipeline with a fiber-reinforced composite sleeve is investigated. The results enable operators to handle problems of corroded steel pipelines and develop effective repair activities during operation. For this reason, current research is important for the maintenance of underground steel networks.
Highlights
Magnetic flux leakage (MFL) technology using axial excitation of magnetic field lines is the most effective and widespread in-line inspection method for longdistance high-pressure underground pipelines [1]
A three-step methodology was employed in [3] as a useful tool for operators to evaluate the severity of part-wall metal losses and aging process of underground steel pipelines that transport natural gas
The aim of this study is to investigate the strength of pipelines containing volumetric defects due to general and pitting corrosion observed by in-line inspection
Summary
Magnetic flux leakage (MFL) technology using axial excitation of magnetic field lines is the most effective and widespread in-line inspection method for longdistance high-pressure underground pipelines [1]. The estimates of state variables such as pressure, temperature and flow rate might too much deviate from the reality To handle this problem, an ensemble data assimilation approach is implemented. The decrease in the tube wall thickness caused by electrochemical corrosion is analysed considering the limit state of plastic collapse and corresponding maximum operating pressure of the remaining pipe wall residual thickness. This value was compared to the estimated internal pressure obtained from the data assimilation approach at the point of the localized defect. This research enables network operators of steel pipelines subjected to corrosion to handle capacity limitations based on transient pressure calculations
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