Preventive replacement models: an overview and their application in process industries

This paper presents a concise review of the optimisation models for the preventive repair/replacement/inspection of components/assemblies/subsystems with the aim of critically examining their prospects as well as limitations in implementation in heavy process industries. The survey covers models under two major categories: models for single-unit systems and for multi-unit systems. Single-unit models are presented under three subcategories of two-state models, three-state models and multistate models; multi-unit models encompass models for the grouping of component replacements under three types of replacements: corrective, opportunistic and preventive. Each of the models and their variations are followed by a discussion on implementation problems and prospects particularly in process industries. [Received 23 April 2008; Revised 18 February 2009; Revised 01 May 2009; Accepted 04 May 2009]