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Performing RBI Risk Analysis with Weighted Severities

In the process of evaluating a failure mode, you can quantify the relative risk (criticality) associated with the failure by evaluating the consequences (severity of the effect) and the probability of the failure occurring, assigning values for each factor. If the analysis supports it, you can also assign a detectability value. APM then calculates the relative risk by multiplying the severity by the probability and then by the detectability.

When the relative risk is established, APM calculates the failure mode’s consequence priority using a set of customer-defined rules. The consequence priority rules can be based on the failure mode’s severity, relative risk, downtime costs, downtime duration, or a combination. For example, the Extreme consequence could be assigned to failure modes whose total severity is equal to 5.0.

After you have analyzed the failure modes, you can compare failure modes and identify the relative importance of addressing them. The Risk Assessment view in the Strategy Development Analysis window includes failure mode lists based on criticality, consequence priority, severity, and relative risk, as well as a risk plot, risk matrix, and lists of the evaluations. This view is also available for the asset.

APM provides two ways to perform risk analysis:

•	Using a simple evaluation that allows you to enter weighted severity values, probability values, and confidence factors.

•	Using evaluation forms for in-depth analysis of consequences and confidence factors.

With both methods, APM calculates the relative risk and displays it in the risk matrix chart. The method available in the Maintenance action plan window depends on the option selected in risk analysis settings.

For instructions on using evaluation forms, see Performing Risk Analysis for RBI Failure Modes.

Note: Before you can perform risk analyses, the severities, probabilities, failure mode consequence priorities, confidence factors, and risk matrix entries must be set up in the site’s strategy development settings. For more information, see Risk Analysis Settings.

To Perform Risk Analysis Using Weighted Severities

1.	Open the analysis, select the Facilitation view, and open the failure mode. The Maintenance action plan window appears.

2.	Select the Criticality view.

3.	Make sure that editing is enabled.

4.	Select a severity value for each of the categories:

•	Economic: The economic consequence of failure reflects the financial effect of the failure on assets and production. Labor and material costs associated with lost production and with repairing or replacing the damaged equipment are economic consequences.

•	Health and safety: Equipment failure can cause hazards in the workplace. Examples are extreme temperatures, noxious fumes, and the release of liquids that can kill or injure someone.

•	Environmental: There is an unacceptable risk that the effects of this failure mode could breach a known environmental standard or regulation.

•	Reputation: The impact that negative media attention has on an organization’s ability to operate in good faith. Typically, the severity of bad press is evaluated in terms of how far-reaching it is and how long it takes to mitigate.

5.	Enter weighting factors for the consequence categories as needed. A weighting factor must be between 0.10 and 2.00. The default is 1.00.

APM calculates the total severity for each of the categories by multiplying the severity by its weighting factor. The failure mode’s total severity is calculated as the sum of the categories’ severities.

6.	If probability can be based on the analysis team’s estimate of the time between failures, the Criticality view also displays the ETBF box:

Enter the amount of time and the unit of measure. The corresponding probability value is displayed in the Probability box.

7.	You can select a probability of failure from the list. If ETBF is also available, its value changes accordingly.

8.	If detectability is supported, select a value from the Detectability list.

APM calculates the relative risk for the failure mode by multiplying the total failure mode severity, by the probability of failure, and then by the detectability number.

When you have entered all of the information that is required by consequence priority rules, APM calculates the criticality number. The risk matrix entry is shown in the risk matrix chart.

9.	Select the most important consequence from the Dominant consequences options.

When you have performed risk analyses for all of the failure modes in the analysis, you can compare them using the Risk Assessment view. For more information, see Viewing Risk Analyses for RBI Failure Modes.