Article on maintenance policy for plant productivity

Question

Write an article on the maintenance policy for overall costs and enhancing plant productivity.

Answer 1

Maintenance policy for plants plays an important role in reduction of overall operating costs and enhancing the plant productivity. A proper maintenance policy strategy will replace deteriorated system before failure and must have different policies for each piece of a system based on the available resources. Previous studies have proposed reliability centered maintenance approach, integrated multi criteria decision making approach and others for determination of a maintenance policy. Bertolini & Bevilacqua (2006) had proposed a lexicographic goal programming (LGP) or a combined AHP-GP approach to define the best maintenance policy strategy which was developed from the previous studies.

The combined approach was applied to determine the optimal maintenance policy for a group of centrifugal pumps in an Italian oil refinery plant. 10-year data regarding failures and maintenance such as failed items, failure cause and effect, repair cost, MTBF and MTTR for 10 most important pumps of the refinery were obtained from the Computerized Maintenance Management System (CMMS) and analyzed. The best maintenance policy for each failure type was determined accounting for the possibility of various alternatives. The criteria decided to be employed were occurrence, severity and detectability. Pair wise comparison was performed to assess the priority of the criteria and the inconsistency ratio was determined. AHP chose severity as the most relevant criterion.

Three maintenance policies namely corrective, preventive and predictive were proposed with resource constraints on budget and labor available and GP model was employed to link the criterion weightings with failure types for the 10-year data and later the best maintenance policy was determined as predictive policy with the second being preventive. The proposed model has emphasized on reduction of failure effects in terms of safety as well as cost and resource usage. Corrective maintenance policy was never suggested in any situation and hence the management focused on introducing a more accurate inspection plan for reducing the catastrophic failures, facilitating better maintenance and at the same time improving cost control and operational efficiency.

The combined model has been proved to be a more flexible tool in optimal resource allocation for various maintenance strategies, with flexible options to vary the objectives and constraint conditions. Bertolini & Bevilacqua (2006) had thus applied AHP-GP approach for a successful selection of maintenance policy and had recommended for the addition of more goals or constraints into the model for future research.