(109f) Optimisation of Preventive Maintenance in the Process Industry

This paper presents a systematic methodology for optimising the Preventive Maintenance (PM) interval based on mathematical programming. Failure Modes and Effects Criticality Analysis (FMECA) is used to identify the critical components with critical failure modes in a process. The Weibull distribution model is applied to present the failure rate of the critical component and on this basis, a new methodology is developed to describe the relationship between reliability and PM interval. The optimisation is to minimize the process lost production cost in a defined period. A case study is presented regarding a LNG process with capacity 50t/hour. The critical equipment in the process is found by conducting FMECA. The optimal solution obtained is compared with the solution in practice. Different economic scenarios can impact the optimal PM solution when optimised. This demonstrates that it is crucial to understand the economics scenarios involved and to account properly for the relevant cost implications. It is important to consider reliability availability and maintainability study at the process conceptual stage design. The improvement in plant availability from choosing the right process configuration in first place can easily overcomes the additional capital investment.