A planning model for inspection and replacement of pipes in a refinery plant

Kyungjae Tak, Junghwan Kim

Research output: Chapter in Book/Report/Conference proceedingChapter


Corrosion is a major safety issue that can lead to unexpected failures in refinery plants. Ensuring the safety of refinery processes from corrosion requires regular maintenance procedures such as the inspection and replacement of pipes, which are essential tasks. Performing maintenance tasks more frequently reduces the failure cost of the process by enhancing the process safety and reliability, but this leads to increased costs of inspection and replacement. Therefore, there is an optimal point that minimizes the total maintenance cost (including inspection, replacement, and failure) while satisfying the minimum safety level limit. The objective of this study is to determine the optimal planning by changing and adjusting maintenance variables such as the initial pipe wall thickness, the number of inspections, and the inspection time. The first step in achieving this goal is the development of a probabilistic model that calculates the total maintenance cost as a function of the remaining pipe wall thickness with the first order reliability method. The remaining wall thickness is decreased by corrosion over time, which affects the total cost. The next step is to minimize the total maintenance cost of the model. A mixed integer nonlinear programming (MINLP) algorithm was employed to perform the optimization. The optimal inspection time, number of inspections, and the initial wall thickness were determined for various corrosion rates. A periodic inspection case that had the same time interval between inspections was also studied.

Original languageEnglish
Title of host publicationChemical Engineering Transactions
EditorsSerafim Bakalis, Laura Piazza, Sauro Pierucci, Jiri Jaromir Klemes
PublisherItalian Association of Chemical Engineering - AIDIC
Number of pages6
ISBN (Electronic)9788895608488
Publication statusPublished - 2017

Bibliographical note

Publisher Copyright:
© Copyright 2017, AIDIC Servizi S.r.l.

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)


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