«Enhance of ship safety based on maintenance strategies by applying of Analytic Hierarchy Process» DAGKINIS IOANNIS, Dr. NIKITAKOS NIKITAS University of the Aegean, Dept. of Shipping Trade and Transport 4th International Symposium "MASSEP 2013" Maritime Safety, Security & Environmental Protection 2013

Equipment Maintenance Strategy The equipment maintenance strategy is one of the factors influencing the safety and overall operational management of the ship. Using the wrong maintenance strategies can waste: Time Money Resources and often has no effect on improving or maintaining availability of equipments. Furthermore the reliability of the ship is reduced, and the risks and the probability of failures increased.

Maintenance Generally accepted approach on maintenance and defines it as: “A combination of any actions carried out to retain an item in or restore it to acceptable operational standard”. If there is breakdown, swift actions must be taken to restore the equipment or facility to its “acceptable condition”. Acceptable conditions will include those factors such as, Efficiency (fuel usage, power output, speed, etc.), Production of good quality product/ service, and Safety of operations.

Maintenance With increasing Technology development, the developing of industries automation and the increase of machinery quantity, the volume of investment in company’s tangible assets and machineries has increased significantly. So the maintenance is an inevitable source of cost, and the increase in maintenance department can represent from 15 to 70% of total production costs ( SARKAR BEHERA 2011 ). Ships and the complexed Ship machinery plan requires an optimal maintenance policy mix, in order to increase the plan availability and reduce the operating costs.

Maintenance Programme Generally a maintenance programme must be produced based on operational specific needs and objectives, taking into account the best practice. It is particularly difficult to choose the best mix of maintenance policies on a ship when needed to comply with many factors. The adoption of previous demands creates the need for the operators to select the best maintenance policy for each piece of equipment or system from a set of possible alternatives, i.e. corrective, preventive, opportunistic, condition-based and predictive maintenance policies.

MCDM As an aid to the resolution of this problem, some multi-criteria decision making (MCDM) approaches are proposed in the literature. Almeida and Bohoris, discuss the application of decision making theory to maintenance with particular attention to multi attribute utility theory. Triantaphyllou, suggests the use of Analytical Hierarchy Process (AHP), considering four maintenance criteria: cost, reparability, reliability and availability. Rausand M., Reliability centered maintenance. The Reliability Centered Maintenance (RCM) methodology is a technique which provides a framework for utilizing operating experience in a more systematic way.

Analytic Hierarchy Process In this paper presented a method based on the AHP (Saaty, T.L. 1980) approach. AHP is a decision making technique, which enables the manipulation of both qualitative assessments, and quantitative metrics from estimations or recorded data in order to improve final judgments for selection of maintenance strategy to select the most appropriate maintenance strategy.

Analytic Hierarchy Process

Intensity of importanceValue descriptionExplanation 1Equal importance.i and j are equally important 3weak importance i is slightly more important than j 5strong importance i is strongly more important than j 7Very strong importance. i is very strongly more important than j 9extreme importance i is absolutely more important than j 2,4,6,8Intermediate values When a compromise in judgment is needed. Scale used for pairwise comparisons.

The model AHP for EMS Operational- Endanger of Operational Degree Analysis of Maintenance Requirements Predictive Corrective Preventive Personnel Selection Selecting of Maintenance Technology Risk Evaluation in Equipment Maintenance Strategies Goal Criteria Alternatives

Defining alternatives E MS Calculate relative importance weights of matrices Define criteria for evaluation of Equipment Maintenance Strategies Construct pairwise comparison matrices using evaluation numbers Literature review Experts’ opinion Check the consistency of the criteria & alternatives weights Obtain the evaluation criteria and alternatives weights Schematic diagram of the proposed model for Equipments Maintenance Strategy selection

Ship Steering Gear Before Today

Ship Steering Gear

Example of method implementation Operational Endanger of Operational DegreePredictivePreventiveCorrectivePriority Predictive1490,6939 Preventive 1/4170,2533 Corrective 1/9 1/710,0528 Predictive4Preventive1 Predictive is weakly more important than criterion to Preventive Maintenance. Weight: 4 Predictive9Corrective1 Predictive is absolutely more important to Corrective Maintenance. Weight: 9 Preventiv e 7Corrective1Preventive is very strongly more important to Corrective Maintenance. Weight: 7 Alternatives compared with respect to Endanger of Operational Degree. The transfer of weights to the matrix. Construct pairwise comparison matrices using evaluation numbers

0,69390,0810 0,28970,5759 0,25330,1884 0,6554*0,1491= 0,05280,7306 0,05490,1545 0,1205 1,0000 Criteria vs. the Goal Operational Endanger of Operational Degree Personnel Selecting Analysis of the Maintenance Requirements Selecting Maintenance Technology Operational Endanger of Operational Degree /313 Operational Endanger of Operational Degree 1/9 1/315 Operational Endanger of Operational Degree 1/73 1/51 Synthesizing final priorities Priority with Respect to Operational Endanger of Operational Degree Personnel Selecting Analysis of the Maintenance Requirements Selecting Maintenance TechnologyGOAL Predictive0,39960,01210,01250,03490,4591 Preventive0,14590,02810,02910,07900,2820 Corrective0,03040,10890,11290,00660,2588 Totals0,57590,14910,15450,12051,0000 The results for choose the best alternative Calculate relative importance weights of matrices

Operational- Endanger of Operational Degree Analysis of Maintenance Requirements 0,1545 Predictive 0,4591 Corrective 0,2588 Preventive 0,2820 Personnel Selection 0,1491 Selecting of Maintenance Technology 0,1205 Risk Evaluation in Equipment Maintenance Strategies

Conclusions The Integrated simulation AHP modeling applied on a ship machinery system with complex service times and maintenance priorities, and that integrated simulation AHP approach of this study may be applied for other similar machinery systems. The AHP it’s a powerful and flexible multi-criteria decision making tool and allows decision makers to model complex problems where both qualitative and quantitative aspects need to be considered. The results and satisfaction from choosing maintenance strategy of certain equipment derived by using the AHP method confirms that it can improve and represents an effective approach to arrive at making decisions

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