Multivariable Based Decision-making for the Maintenance Strategy of Process Equipment

Nowadays, several pieces of equipment are running over their expected life-time. An equipment revamping could solve the situation, but, it is often not possible for economical reasons, regulatory constraints, etc.. The aging of the equipment can also cause safety problems: between 1980 and 2006, the Health and Safety Executive estimated that around 28% of the major incidents occurred in the period, corresponding to 96 accidents, could be traced back to plant aging. These accidents costed more than 17,000,000 € (Horrocks et al., 2010). A correct maintenance of the equipment can extend the plant life, increase the plant efficiency and maintain an adequate level of safety. Plant management can choose among different maintenance strategies. The choice can be influenced by parameters as: the maintenance cost, the equipment condition before the maintenance, the lack of production cost, the safety of the operator during the maintenance and during the normal operations. In this paper, a multivariable Fuzzy approach is proposed in order to support the decision between different maintenance strategies through the analysis of their peculiarities, helping the management to weight the pros and cons of the alternatives. This approach is applied to a case study related to the maintenance of process equipment: it highlighted that the full refurbishment of a turbine blades system is a maintenance approach as valid as the current maintenance procedure, while the adoption of new technologies resulted not convenient.