A multi-constrained maintenance scheduling optimization model for a hydrocarbon processing facility

A maintenance scheduling optimization model considering equipment risk, total maintenance cost, system reliability and availability is proposed. This work is motivated by gas processing operator's concern of high maintenance cost, poor availability and reliability caused by inefficient maintenance scheduling. The approach presented in this article addresses the optimization of maintenance cost by efficiently scheduling maintenance task subject to reliability and availability constraints. Four maintenance actions are considered for each equipment, namely, corrective, replacement, maintenance and inspection. The proposed solution develops maintenance schedules for complex repairable system with equipment operating in series. Two single-objective, nonlinear mathematical models are presented to find the optimal maintenance cost subject to reliability and system reliability subject to availability constraint. A goal programming model is also proposed to simultaneously deal with multiple criteria based on their importance and defined goals. A gas absorption system of a hydrocarbon processing facility is used to ensure the practicality of the proposed formulation to real industry problems. A comparison of existing and proposed formulation is carried out to show that the proposed optimization approach is an efficient method for optimizing maintenance schedules and flexibility to adjust schedules in a complex operating system.