- Buyer's Guide
When establishing a preventive maintenance (PM) program, there are a few ideas that can help support your reliability objectives without incurring unnecessary costs. The tips below apply to both condition monitoring and routine servicing.
Ensure the equipment components being inspected have failure modes that make condition monitoring inspections worthwhile. If the components are likely to fail quickly (fuses and shear pins come to mind), inspections are of no value.
Set condition monitoring inspection frequencies so that almost all probable failures will be detected in time to make the required repairs during scheduled shutdowns and before a breakdown occurs. The time between inspections should be less than half of the "failure development time," which is the elapsed time from when a failure first starts to become apparent until the component ceases to function.
Failure development times depend on the type of component and its operating context (load, speed, etc.). For some equipment, this information may be available from the manufacturer. For others, it comes from experience. Predictive maintenance techniques, such as vibration and oil analyses, extend the failure development period by detecting failures earlier and by monitoring the rate of deterioration prior to breakdown.
Make sure your equipment is in good condition before you start routine PM inspections and servicing. For example, consider a plain bearing that is grease-lubricated. If the running clearance is within the manufacturer's tolerances, then lubricating at the recommended frequency will keep it in good operating condition. However, if the bearing has been neglected and has worn significantly, the resulting metal-to-metal contact will cause accelerated wear to continue, even with regular lubrication.
Set up inspection routes that make it easy for inspectors. For example, match the estimated time to complete a route to normal work breaks. Four two-hour inspection routes are normally easier for the inspector to manage than one eight-hour route.
You should also minimize the administrative effort. Hand-held instruments may assist by advising the inspector of an existing work order for a "found" failure, providing equipment history in the field and recording failures.
Routes should provide all the needed information, including the equipment’s location and its isolating devices if it needs to be locked out to inspect or service.
In addition, be sure to design the inspection/servicing route to minimize the travel required, including climbing stairs, etc.
Skilled tradespeople do not always make the best inspectors. Most inspections do not require a high level of skill. Selecting people who have a natural interest in routine work and in taking responsibility for an area will provide better results.
This is essential. The PM scope and frequency should be under continuous review to ensure that the amount of PM work being done is minimized without jeopardizing reliability. This is a skilled balancing act requiring disciplined technical leadership.
Whenever a breakdown occurs, the PM specialist should decide if a program change is needed to prevent it from happening again.