Condition Monitoring Expert Tip #3 - Criticality Analysis is Critical

How do you decide which assets should be monitored? How do you decide whether you can justify the use of more than one technology? Criticality analysis provides a means to prioritize which assets will be monitored and how much effort will be put in to collecting data and performing the analysis.

Criticality analysis considers several factors. It will consider the consequences of failure, for example health and safety, harm to the environment, downtime and production losses, availability of spares, cost of spares, etc. It will also consider the reliability of the asset; how likely is it to develop a fault condition. And it should also consider the detectability of the fault conditions. Therefore, an unreliable asset where failure would lead to dire consequences and where we currently cannot detect the onset of failure absolutely requires condition monitoring and can justify multiple technologies. At the other extreme, a reliable asset’s minimal consequences of failure may not require any condition monitoring; we may employ “run to failure”.

Criticality analysis enables you to make the best use of your limited resources.

This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.

Condition Monitoring Expert Tip #2 – How Often Should Measurements Be Taken?

How do you decide how often measurements should be taken?

Regardless of the condition monitoring technology, you must decide how often measurements will be taken. At one extreme, it could be a permanent monitoring system that takes measurements every split second of every day. At the other extreme, it may be infrared analysis that is performed once a year. But how do you make that decision?

The most common answer we receive is that it is based on the criticality of the equipment. More frequent measurements are taken on the more critical equipment. The next most common answer is that it is based on reliability. If you have been monitoring a machine with vibration analysis every 30 days and have not detected a fault for a year you may decide to test it every 60 days, or 90 days. Now, it is true that you have to decide how best to use your precious time. But the one factor often forgotten is the “PF interval”.

The PF interval, also known as the “lead time to failure”, is the time between when you can detect the fault condition and when the equipment will have “functionally failed” – i.e. it can no longer be used. If we use the right technologies with the correct settings and we take frequent measurements, then we will get the earliest warning, and therefore we have the greatest lead time to act. However, if the PF interval is short, then it is possible that if you have extended the measurement period to 90 days, the equipment may develop a fault and fail before you take the next measurement.

There is a lot more that could be said on this topic but suffice to say that it is essential that you understand the PF interval and continue to monitor equipment so that you take at least two measurements between the time the fault is detectable and when the asset will have functionally failed.

This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com.

Condition Monitoring Expert Tip #1 – Which Technologies Should You Use?

How do you decide which condition monitoring technologies to use?

There are many condition monitoring technologies that we could employ. And within each technology there are sub-technologies. For example, within vibration analysis we can use high frequency analysis, spectrum analysis, time waveform analysis and phase analysis. Within each sub technology there are settings we must select. For example, we must set the frequency range when collecting spectra. But which technologies should we use? Which settings are correct? The best way to make those decisions is by understanding the failure modes of the equipment.

If you understand what leads to failure, and what is likely to fail, you can select the most appropriate technologies and settings. You may argue that that is an obvious statement to make. You are probably not using vibration analysis on your steam traps… But after 30 years of experience in vibration analysis, it is common to see that fault conditions a totally missed because of the misapplication the technology.

It is not necessary to perform a full RCM (reliability centered maintenance) or FMEA (failure modes effects analysis) to make this determination. A so-called “accelerated RCM” is sufficient to ensure that you make the right decisions.

This tip is provided by Jason Tranter, Managing Director of Mobius Institute.

For more condition monitoring tips, continue to visit the IMVAC – International Machine Vibration Analysis Conference – blog every week. To learn more about IMVAC and the event nearest to you, visit vibrationconference.com or call Kaitie Conly at (1) 615-216-4811 ext. 3.