About Qualitative Risk Rank Mapping from LOPA

GE Digital APM maps the quantitative values calculated using LOPA with the Risk Matrix configured for the site to which the LOPA belongs, and then assigns the unmitigated risk in the Risk Matrix. The following values in the LOPA are used to derive at the unmitigated risk rank:

• Risk Category: The value in the Risk Category field in the LOPA identifies the category of the driving risk associated with the initiating event. This value is mapped to the Risk Category in the Risk Matrix.
• Risk Severity: The value in the Risk Severity field identifies the severity of the impact and is mapped to the Consequence value in the Risk Matrix.

• Unmitigated Consequence Frequency: The value in the Unmitigated Consequence Frequency field is mapped to the Probability value in the Risk Matrix in one of the following ways:

  • The Probability that is equal to or less than the unmitigated consequence frequency is selected as the Probability for the Risk Matrix.
  • If the unmitigated consequence frequency is lower than the lowest Probability defined in the Risk Matrix, the lowest Probability is selected as the Probability for the Risk Matrix.

Note: GE Digital APM assumes that you have created the Risk Matrix for your site using probability values that have been standardized to be measured in terms of years.

Based on the Probability and Consequence values, GE Digital APM identifies the unmitigated risk rank associated with the selected Risk Category. A Risk Assessment record, which stores details such as the driving risk category and the unmitigated risk rank value, is created and linked to the LOPA.

If you assess the SIL value for an Instrumented Function using a LOPA that is linked to a Risk Assessment, and then create a recommendation for the Instrumented Function, the Mitigated Risk section appears in the Recommendation. In the Mitigated Risk section, the following details appear:

• Total Risk: Contains the unmitigated risk rank stored in the Risk Assessment associated with the LOPA.
• Driving Risk: Contains the Risk Category that you selected in the LOPA.
• Driving Risk Threshold: Indicates the Risk Threshold value for the unmitigated risk rank.

On the Risk Matrix, in the Risk Category that you selected in the LOPA, the icon appears on the cell corresponding to the unmitigated risk rank. You can then select the mitigated risk rank for the category.

Suppose that you have configured a Risk Matrix for Site X with the following values in Risk Probability records for the Risk Category Operations:

Risk Probability Name	Probability	Failure Interval	Failure Interval Units
Frequent	1	1	years
Probable	0.1	10	years
Possible	0.01	100	years
Remote	0.001	1000	years
Improbable	0.0001	10000	years

In Site X, suppose that you created a LOPA with the following details:

• Risk Category = Operations
• Risk Severity = High
• Unmitigated Consequence Frequency = 0.005

For the above example, the probability value in the Risk Matrix that is less than the unmitigated consequence frequency is 0.001. Therefore, on the Risk Matrix, the unmitigated risk will be mapped to the cell corresponding to Probability value 0.001 and Consequence value High.

Suppose that you have configured a Risk Matrix for Site X with the following values in Risk Probability records for the Risk Category Operations:

Risk Probability Name	Probability	Failure Interval	Failure Interval Units
Frequent	5	.2	years
Probable	1	1	years
Possible	0.3	3.33	years
Remote	0.1	10	years
Improbable	0.05	20	years

In Site X, suppose that you created a LOPA with the following details:

• Risk Category = Operations
• Risk Severity = Medium
• Unmitigated Consequence Frequency = 0.001

For the above example, the unmitigated consequence frequency is lower than the lowest probability value (i.e., 0.05) in the Risk Matrix. Therefore, on the Risk Matrix, the unmitigated risk will be mapped to the cell corresponding to Probability value 0.05 and Consequence value Medium.