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Setting up RCA Recommendation Thresholds

Using the Failure window’s RCA view, you can evaluate a failure’s suitability for root cause analysis, based on the failure’s criticality index. APM calculates the criticality index as follows:
Criticality Index = Consequence priority * Failure Severity * Probability of Recurrence
The value of the criticality index, in turn, determines whether RCA is required, recommended, or not required.
This topic explains the elements of the failure evaluation tool and how to set up the RCA recommendation thresholds.

Consequence Priority

During the evaluation, the team specifies whether the failure is evident or hidden. Then they determine the failure’s consequence priority by selecting severity values for the health and safety, environmental, and economic consequences. For example:
Note: If the failure references a failure mode, severity values are copied from the failure mode’s risk analysis to the failure’s Consequences tab.
APM calculates the consequence priority by multiplying the severity values by their weighting factors and then applying a rule to the result. For example, the following rule could assign a consequence priority of “Medium”.
Any of(Environmental, Economic, Safety) Is equal to 3.00
Rules can also include the failure record’s downtime and failure costs. The larger the consequence priority number, the greater its priority.

Criticality Index

The criticality index is calculated by multiplying the numbers assigned to the consequence priority, failure severity, and probability of recurrence. For example:

Recommendation

The failure’s evident/hidden value and its criticality index determine the RCA recommendation.
The recommendation is determined by the position of the criticality index value in the recommendation thresholds.
Possible recommendations are:
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RCA not required
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RCA recommended
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RCA required
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RCA evaluation not performed

Setting up the Evaluation

To set up the evaluation, the following values must be defined:
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Severities for health and safety, economic, and environmental consequences. Because severities are also used in risk analysis, they can be defined in strategy development settings. APM comes with basic severities for each of the categories. You can add impact statements, adjust severities as needed, and add your own. See Setting up Severities.
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Consequence priorities, including the rules that assign RCA ranking scores. APM comes with defined priorities. You will need to add RCA scores to them. Because priorities are also used in risk analysis, they can be defined in strategy development settings. For more information, see Setting up Consequence Priorities.
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Failure severities for potential, partial, and full failures. Assign each severity a sequence number to indicate its ranking, as well as a number to indicate the seriousness for RCA. For more information, see Defining Failure Severities.
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Probabilities of recurrence, including scores to be used in calculating the failure’s criticality index. To create probabilities, see Setting up Probability of Recurrence Values for RCA.
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RCA recommendation thresholds, explained next.

RCA Recommendation Thresholds

For each of the consequences, specify the range of criticality indices for hidden and evident failures. The ranges work like this:
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An index that is equal to or greater than the top of the range has the recommendation “RCA required”.
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An index that is less than or equal to the bottom of the range has the recommendation “RCA not required”.
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An index between the top and bottom has the recommendation “RCA recommended”.
Failures that result in health and safety consequences typically have equal weight with environmental consequences. Hidden failures are given more attention than evident ones. Here is an example of recommendation thresholds.
Consequence
Hidden/
Evident
RCA Not Required
RCA Required
RCA Recommended
Health and Safety
Hidden
≤ 2
≥ 10
3-9
Health and Safety
Evident
≤ 4
≥ 10
5-9
Environmental
Hidden
≤ 2
≥ 10
3-9
Environmental
Evident
≤ 4
≥ 10
5-9
Economic
Hidden
≤ 2
≥ 6
3-5
Economic
Evident
≤ 4
≥ 8
5-7
Other
Hidden
≤ 1
≥ 10
2-9
Other
Evident
≤ 10
≥ 12
11
The first set of thresholds that apply to the failure is used.

To Set up RCA Recommendation Thresholds

1.
From the Site window, select the Performance Management view, Settings tab. Select the RCA tab and the RCA settings node in the tree.
Tip: You can also click the Administration menu, Performance Management Settings, and then RCA. The RCA Management Settings dialog appears.
2.
Select the Policies tab.
3.
Click Edit to modify the site settings. The Edit button is replaced by the Save button.
4.
For each of the types of consequences, enter a threshold number in the Hidden and Evident boxes.
5.
Click Save.