What is a failure finding task?
Failure finding tasks, used in reliability-centered maintenance, reveal hidden failures or potential failures.
A failure finding task is part of a comprehensive routine maintenance program. It affects the components of a system that are not readily seen during a routine inspection or addressed during preventive maintenance work. They usually have a protective function in the overall system and can make up 40 percent of failure modes.
Because these failures do not show themselves as clearly as other mechanical or electrical problems, they need to be sought out by maintenance technicians using a prescribed procedure and on a specific timeline. For example, one failure finding task may be to check the operation of a backup generator. A facility would not know that a backup piece of equipment failed to work until the primary machine broke down, compounding the effects of the failure.
A wide variety of organizations apply failure finding tasks. Any piece of equipment that needs to function in an emergency or as a backup should be subject to failure finding tasks. In addition, a switch or alarm that has a protective function and needs to be triggered by another event would require failing finding maintenance.
Example of a failure finding task
A failure finding task needs to test all the potential circumstances in which a protective device would malfunction. For example, an electrical circuit system is complex and would require failure finding, or detective tasks, to be performed throughout the entire system.
A maintenance technician would start from the sensor and work all the way through the actuator, replicating all the possible conditions that could lead to a malfunction of a protective device.
One example would be the pressure switch that shuts down the machine if the oil pressure falls to a dangerous level. In order to test this switch, the technician should actually drop the oil pressure to see if it triggers the correct response.
How to find hidden failures
In order to find hidden failures successfully and address them effectively, organizations should consider the following items:
- If there are no cost-effective ways to test and prevent the failure within a regular preventive maintenance program, a failure finding task is warranted
- The detective task must be technically feasible and practical to perform in a testing mode without significant disruption to an operating line
- By completing the failure finding task, the facility must be able to reduce the chance of malfunction to a reasonable level.
- Failure finding tasks must not increase the probability of other failures during the testing phase
- These tests must be completed to check the entire functioning of a protective system and not only a single part
- The cost of conducting the failure finding tasks must be less than the cost resulting from a malfunction as long as safety requirements are met.
Types of hidden failures tasks
Failure finding tasks are performed on protective systems throughout a plant or facility. Typical types of hidden failures may be found in the following areas:
- Alert or alarm systems: These systems are designed to trigger a sound or light warning when a problem occurs somewhere in the system.
- Relief systems: These valves or other triggers prevent a larger problem within a machine or piece of equipment by relieving pressure before an overflow or explosion occurs.
- Shutdown systems: These components stop a system when certain overloads occur to prevent the destruction of a more expensive component such as a motor.
- Mitigation systems: These systems are designed to quickly address a resulting problem from another system failure. Fire extinguisher equipment would fall into mitigation systems.
- Back-up systems: These machines are designed to keep an entire line or piece of equipment up and running if the primary component or machine fails.
- Guarding systems: These components are designed to prevent an accident due to an equipment malfunction. They may trigger an automatic stop or guard protection in certain cases.