Maintenance Technology September 2016 - 71

10 The RCM process entails asking seven questions about the asset or system under review, as follows: * What are the functions and associated performance standards of the asset in its present operating context? * In what ways does it fail to fulfil its functions? * What causes each functional failure? * What happens when each failure occurs? * In what way does each failure matter? * What can be done to predict or prevent each failure? * What should be done if a suitable preventative task cannot be found? The strength of RCM is the way it provides simple, precise and easily understood criteria for deciding which (if any) predictive and/or preventative tasks are technically feasible in any context and if so for deciding how often they should be done and who should do them. In addition to a preventative task's technical feasibility, whether it is worth doing is governed by how well it deals with the consequences of the failure. If a preventative task cannot be found that is both technically feasible and worth doing, then a suitable default action must be taken. The essence of the task selections process is as follows: * For hidden failures, a predictive and/or preventative task is worth doing if it reduces the risk of the multiple failures associated with that function to a tolerably low level. If such a task cannot be found, a scheduled failurefinding task must be performed. If a suitable failure-finding task cannot be found, a secondary default decision is reached and will require a redesign. * For failures with safety or environmental consequences, a predictive and/or preventative task is only worth doing if it reduces the risk of that failure on its own to a very low level, if it does not eliminate it altogether. If a task cannot be found that reduces the risk of the failure to a tolerably low level, the item must be redesigned or the process must be changed. * For failures with operational consequences, a predictive and/or preventative task is only worth doing if the total cost of doing it, over a period The strength of RCM is the way it provides simple, precise and easily understood criteria for deciding which (if any) predictive and/or preventative tasks are technically feasible in any context and if so for deciding how often they should be done and who should do them. of time, is less than the cost of the operational consequences plus the cost of repair over the same period of time. If this is not met, the initial default action is no scheduled maintenance (if this is met and the operational consequences are still unacceptable then the secondary default action is to redesign). * For failures with non-operational consequences, a predictive and/or preventative task is only worth doing if the total cost of doing it, over a period of time, is less the cost of repair over the same period, otherwise, no schedule maintenance (if the repair costs are too high the secondary default action is to possibly redesign). All too often operations and maintenance policies lead to practices used for all similar assets without considering the consequences of failure in different operating contexts. This results in large numbers of maintenance SOLUTIONS AUGUST 2016 10127-4056 SMRP Solutions SE.indd 10 8/22/16 9:43 AM

Table of Contents for the Digital Edition of Maintenance Technology September 2016