Browsing by Author "Swart, Petrus Daniel"

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    An asset investment decision framework to prioritise shutdown maintenance tasks
    (Stellenbosch : Stellenbosch University, 2015-12) Swart, Petrus Daniel; Vlok, P. J.; Jooste, J. L.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
    ENGLISH ABSTRACT: The 2007-2008 Global Financial Crisis and subsequent economic downturn have forced many asset-intensive organisations to direct their maintenance efforts towards achieving their strategic goals more efficiently and effectively. Hence, these organisations can ill-afford to perform non-critical maintenance before or instead of critical maintenance. This is especially true for their shutdowns, which are typically short and expensive maintenance driven projects characterised by strict time and budget constraints. In this study, a new framework is developed to prioritise the maintenance tasks proposed for an upcoming shutdown on a critical asset. Limited maintenance resources, such as time and budget, are considered in the prioritisation process, in addition to the value delivered by each maintenance task. Value is measured in terms of return on investment, which is the reduction in risk cost achieved by performing a combination of maintenance tasks on the asset relative to the costs incurred. The developed framework selects the combination of maintenance tasks that delivers the greatest return, whilst adhering to the aforestated constraints. The developed framework is a modification of an existing generic maintenance prioritisation framework found in literature. This generic framework is modified through the incorporation of an Imperfect Maintenance age reduction factor which quantifies the value delivered by each maintenance task performed. Moreover, four well established Multiple Criteria Decision Analysis models, namely the additive and multiplicative value functions as well as the ELECTRE II and PROMETHEE II methods, are incorporated to effectively prioritise the combinations of maintenance tasks. A case study conducted at a South African thermal coal mine was used to validate the developed framework. Through a comprehensive case study scenario analysis, different possible shutdown scenarios were evaluated in order to help the thermal coal mine remain flexible in its decision making during the months leading up to the shutdown of one of its most critical assets. The results indicate that the developed framework is a useful tool to assist the selection of shutdown maintenance tasks that best suit the needs and objectives of the asset and organisation respectively.