Asset KPIs

4 Important Asset KPIs worth tracking

This blog explains how productivity and efficiency can be improved through asset Key Performance Indicator(KPI) tracking. The blog provides information about plant and refinery optimization, KPI calculations, examples, and tips.

Asset KPIs contain interesting information about the performance of an asset. Performance KPIs provide operators and managers insight into asset uptime, breakdown rates, and accuracy. With this information, maintenance schedules can be optimized, and downtime minimized. The important KPIs are:

  • 1. Mean Time Between Failures (MTBF)
  • 2. Mean Time To Repairs (MTTR)
  • 3. Overall Equipment Effectiveness (OEE)
  • 4. Unplanned Maintenance Percentage (UMP)

Mean Time Between Failures

MTBF is a way to predict the time between failures of an asset during regular operating hours. MTBF is the average time between breakdowns. It is a crucial metric to measure the reliability and safety of assets. Tracking MTBF allows operators and managers to anticipate future breakdowns by analyzing asset failure and maintenance history. Successful tracking of MTBF provides the opportunity to prevent the next failure with preventive maintenance. The benefits are extending the asset life, improving efficiency, and cutting costs.

Mean Time Between Failures calculation

MTBF = Total uptime / Number of breakdowns.

For example, the run time for a year is 8.736 hours. In that year, the refinery faced 4 breakdowns with a total of 60 hours of downtime.
MTBF = (8.736 – 60) /4 breakdowns
MTBF = 2.169 hours

What can be done with this information?

On average, the asset runs 2.169 hours before breaking down, which equals 90 days. The asset should receive preventive maintenance around four times each year to prevent future breakdowns in this scenario. It requires more information like root cause analysis to ensure that this estimation is accurate, but MTBF does provide a basis on which an initial schedule can be created. This approach reduces the need for daily visual inspection and improves the efficiency of maintenance planning.

Mean Time To Repair

MTTR is the opposite of MTBF. MTTR analyzes how long it takes to resolve breakdowns, and MTTR is a powerful KPI to determine the severity of breakdowns. If the MTTR is low, then the conclusion can be made that it can be resolved with preventive maintenance scheduling. If the MTTR is high, it might be an option to look for a different way to reduce maintenance by replacing the asset or changing the process. MTTR can also be used to compare the performance of different technicians by calculating each staff member’s mean time to repair a common asset and/or issue. MTTR shows how quickly the maintenance team can respond to and repair unplanned downtimes. This includes:

  • – How fast is the issue identified
  • – What is the issue
  • – Is there a known solution
  • – Repairing, aligning and validating the asset
  • Releasing the asset for production


Mean Time To Repair Calculation

MTTR = total maintenance time / total number of repairs
For example, the total breakdown time is 60 hours, and the number of repairs is 4.
MTTR = 60/4 repairs = 15

What can be done with this information?

With an average of 15 hours to repair and a MTBF of 2169, there is an average downtime rate of 15/2169*100 = 0.69 %
This means the severity of maintenance is low and preventive maintenance will most likely be sufficient in keeping this asset running.

Overall Equipment Effectiveness (OEE)

OEE is a KPI about asset effectiveness based on three categories: availability, performance, and quality. The score of OEE is from 0 to 1, where 0 means ineffective and 1 means effective. Determining an asset’s effectiveness is useful in replacement or repair decisions and determining the preventive maintenance schedule based on OEE decay.

Overall Equipment Effectiveness Calculations

OEE = availability x performance x quality
Availability = actual operating time / planned operating time
Performance = actual rate of production / planned rate of production
Quality = in spec production / total production

The availability calculation:

For example, an asset is supposed to run 24 hours a day, but today it broke down for 5 hours, which means it was only usable for 19 hours.
Availability = 19/24
Availability = 0.79

The performance calculation:

The planned production for the asset is 800 units every hour, but the actual production was 600 units.
Performance = 600 units / 800 units
Performance = 0.75

The quality calculation:

Of the 600 units, 550 units met the quality expectations.
Quality = 550 units / 600 units
Quality = 0.92

Now we discussed all calculations we need for the KPI Overall Equipment Effectiveness. For the OEE calculations, we need the answers from the previous calculations:
OEE = 0.76 x 0.55 x 0.92
OEE = 0.38

What can be done with this information?

A score of 0.38 would be a very low result, and there should be an investigation of what caused this result. A conclusion could be the short period combined with unfortunate downtime, which would result in a plan to prevent that downtime from happening again. With this score, it provides 3 different ways to collectively improve the effectiveness of the asset and improve on the part where there is most to gain instead of solely focusing on uptime. Slightly lower uptime because of more preventive maintenance can prove to result in more spec production, and less maintenance might result in getting closer to production targets. By analyzing OEE, the maintenance team can strive to find the optimal way of servicing and running the asset.

Unplanned Maintenance Percentage

UMP is a KPI to track how successful the planned maintenance plan is. Unplanned maintenance is inevitable, but a good ratio between unplanned and planned maintenance is a goal to strive for. To avoid unplanned maintenance, the KPI MTBF can be used to implement a preventive maintenance schedule. However, this will not cover all the problems.

Unplanned Maintenance Percentage calculation

Unplanned maintenance percentage = unplanned maintenance / total maintenance x 100%
For example, if the maintenance team performed 60 hours of maintenance on an asset, of which 5 hours are due to unplanned downtime, then the unplanned maintenance percentage is:

Unplanned maintenance percentage = 5 / 60 = 0.083 x100 = 8.3%

What can be done with this information?

In this scenario, the UMP was low, so there is no action needed. An investigation for the cause should be conducted when the UMP is high. That investigation’s potential resulting actions are changing the maintenance plan or replacing the asset.


Tracking these four KPIs is a great way to get information on assets. Using KPIs to track asset maintenance and ultimately optimize asset performance will take the plant/refinery to the next level. In order to monitor and manage these KPIs anywhere and anytime, the operator/manager can consider implementing an Asset Management software tool, Like the AML information management system.

It provides real-time data from online instruments/systems, including process, diagnostic, historical, and maintenance data. AML helps to calculate, monitor, maintain and improve the performance of online assets, like process analyzers. With AML a company can move from problem-solving to problem-prevention.

Learn more about the 5 advantages of cloud-based asset management software.