Multistage Planned Replacement Strategies

For failing type of equipment, multistage replacement strategies, available in literature, specify use of the equipment in the system until its failure. The strategies bring economy by transferring failure rate from groups where the replacement cost is higher to those where it is smaller. A large variety of equipment has monotone increasing failure rate and in such cases planned replacement has significance. This paper presents two types of multistage planned replacement strategies, namely, multistage block replacement strategy and multistage planned replacement strategy by age. Each of these is compared with the corresponding single stage strategy available in literature. The comparison provides the condition of economy and the amount of economic gain. Besides their applications, the two strategies are discussed in relation to each other. Certain means for improving the economy of the strategies, and further work in this field are indicated.