If there are not any technically feasible tasks to predict or prevent the failure in the work conditions, or they are not cost effective, we must perform actions.
These tasks can be Run-to-Failure or Redesign.
- Run-to-Failure, only if the risk of the failure is in acceptable values and has not got safety or environmental consequences.
In these cases we must prepare an emergency response to act once the failure has been. To design this response the probability of the failure and the time between failures must be considered.
The emergency response must be based in a protocol that can include work orders to repair the failures, which allow acting immediately the failure is detected, the actions to take when the failure is detected to affect the failure affected, and the spare parts forecast to use to repair the failure.
- Redesign, if the risk of the failure is out acceptable values and has got safety or environmental consequences we must think in redesign, the redesign can be change in design of equipment, change in process, and change in operations. The redesign can be focused in prevention of failures, avoiding them; detection of failures, before the consequences of failure; control of the failures, reducing the probability of the failures modes; or mitigation, reducing the consequences of the failure.
These redesigns can affect both the equipment and the operation conditions, and the redesigns can include physical modifications of equipment or the environment, change in operation procedures, operation or maintenance staff training, etc.
Before start the redesign we must check that they are cost-effective, comparing the redesign and implantation cost and the estimated risk reduction, this risk never can be reducing to zero but it is right if the risk is reduced to reasonable values, or allows using effective condition based maintenance, time based maintenance or failure finding tasks.
Redesign must be considered as a project, with financial, human and material resources that must be assigned, and must be time limited. Finally, to check the redesign meets the targets should be checked.