Advanced delay-time analysis applied to carbon black powder production

Delay time models (DTM) for series systems divide the failure of a system into the appearance of defects and the delay until the breakdown. During this work, we developed four new DTM whose main novelty consists of considering cheaper online inspections preceding offline inspections. Our numerically tested models were applied to a previously published study about a carbon black factory. After the improvement of problematic assumptions, the optimal inspection period turns out to be considerably larger than in the previous study, which emphasises the need to flexibly develop new delay-time models when facing unusual situations and to avoid a reliance on black boxes. The correct handling of environmental consequences has a tremendous impact upon the optimal maintenance decision.