A robust reliability-based scheduling for the maintenance activities during planned shutdown under uncertainty of activity duration

Abstract Scheduling of the maintenance activities is considered, in which the duration of activities is uncertain, delivery date of the maintenance shutdown is predefined, and activities are multi-mode. The problem is a multi-mode time-constrained project scheduling problem (MTCPSP). The glycol regeneration unit in a gas refinery is as the case study. Based on the effect of equipment or sub-equipment on the system reliability, the importance value of equipment and sub-equipment within the system is determined, and these values are used in a heuristic algorithm as a priority rule for choosing activities in the schedule. Outcomes demonstrate the performance of the algorithm in early or on time delivery of the planned shutdown and reveal that if during the execution of the maintenance shutdown, it is forced to shorten the shutdown period, at each time before the deadline, the plant can be started up with the maximum possible improvement of the system reliability.