The last two decades witnessed major progress in the development of new maintenance strategies. Progress in
the maintenance area has been motivated by the increase in the number, size, complexity, and variety of physical
assets; growing awareness of the impact of maintenance on the environment, safety of personnel, the profitability
of the business, and quality of the products. Unexpected failures usually have adverse effects on the environment and may result in major accidents. Studies by Kletz (1994), Khan and Abbasi (1998), and Kumar (1998) show the close relationship between maintenance practices and the occurrence of major accidents. Profitability is closely related to availability and reliability of the equipment, while product quality is very much dependent on equipment condition.