This study introduces a method that selects equipment, so as to reach the required unavailability level, by carrying out an optimization analysis which considers the reliability data and cost of the equipment. A more practical optimization problem has been formulated using the objective function based on the discrete function and constraints. For the cooling system of a jacketed reactor, an optimization analysis was performed on equipment that have different failure rates depending on their costs in order to reach the target unavailability level required by the system. The integer programming was used for this optimization analysis. When the method developed through this study is used, cost can be reduced and the target level of the system unavailability can be reached by selecting proper equipment for chemical plants through the optimization analysis. This is more cost efficient than the former method of selection, which does not perform any economical analysis thus leading to the usage of overly expensive equipment with low failure rates. (C) 2003 Elsevier Ltd. All rights reserved.