The second tab on the RBI 581 Details Page is the Consequence of Failure (CoF) calculation. Unlike the Probability of Failure (PoF) calculation, the CoF calculation remains the same regardless of the Degradation Mechanism (DM). This calculation is divided into five parts:
Flammable Consequence
Toxic Consequence
NFNT (Non-Flammable, Non-Toxic) Consequence
Financial Consequence
Final Consequence Area
Filling in the CoF data
When you click the Consequence of Failure tab, a form will show.
The CoF form is divided into four sections:
Fluid Details,
Financial,
Mitigation, and
Specifications.
Note that the Specifications section includes a Material field. If the Material as specified in the Component’s Details section has a defined cost factor, this field will point to the Component’s Material and will be read-only. If the Component’s specified material does not have a defined cost factor, you’ll have the option to select a different Material for the CoF.
In addition the Inventory Group Mass and No. of Toxic Components grids will show.
In edit mode, some fields in the form will appear in blue, indicating that they are required for the calculation to work, while the white fields are optional and provide additional information. Even without all the required data, you can still Save and return later to complete the missing fields.
The CoF calculation reference specific CoF data tables. These tables cannot be changed, but can be viewed in Settings\Maintenance\RBI Specific Data.
Mitigation System
In the Mitigation section a Mitigation System can be selected. The API RBI 581 Standard defines four Mitigation Systems, each with its own Consequence Area Reduction Factors. In addition to the four Mitigation Systems, there is also a case where no mitigation applies.
Mitigation System | Consequence Area Adjustment | Consequence Area Reduction Factor, factmit |
|---|---|---|
Inventory blowdown, coupled with isolation system classification B or higher. | Reduce Consequence Area by 25%. | 0.25 |
Fire water deluge system and monitors | Reduce Consequence Area by 20%. | 0.2 |
Fire water monitors only | Reduce Consequence Area by 5%. | 0.05 |
Foam spray system | Reduce Consequence Area by 15%. | 0.15 |
No Mitigation | Reduce Consequence Area by 0%. | 0 |
Inventory Group Mass
Once all the blue fields are filled and saved, the only additional input needed to trigger the CoF calculation is at least one completed Inventory Group Mass record. A default record is automatically added with the current Equipment already selected. You need to enter the Inventory Mass In Equipment or Inventory Mass In Component to complete the record. Alternatively, you can add a new record, and the default one will be removed from the grid (if no Inventory Mass In Equipment or Inventory Mass In Component was entered). You can also choose to keep both records by updating the default record and then adding a new one.
Number of Toxic Components
It's not necessary to input data in the Number of Toxic Components grid for the calculation to work. However, if a value is entered, you will need to do a re-calculation to adjust the results based on the Toxic Components.
Calculating the CoF
When done entering all the data you can click Calculate button in the Consequence of Failure tab to calculate the CoF.
The Calculate button has two states:
Enabled: When all input parameters are filled, and there is at least one record in the Inventory Group Mass grid.
Disabled: When input parameters are missing, or there is no record in the Inventory Group Mass grid.
After the calculation is completed, a notification appears in the top right corner to indicate whether the calculation was successful and the right section of the screen displays the filled-in values for Consequence of Failure, Area, and Economic. If the PoF has also been calculated, the Risk value will appear, and the Risk Matrix in the Results (right) Pane will show two circles. The gray circle represents the current Risk value, while the blue line indicates the Risk Target Criteria. The blue circle represents the Next Inspection Date (NID), and the Maximum Inspection Interval (MII) is the number of years it will take for the Risk to reach the NID, indicated by an upward-pointing arrow.
When the PoF and the CoF has been calculated, the Calculate button in the Results Pane becomes enabled. This is used to calculate the MII and Future Risk Values and Dates for every Probability Class.
When the RBI 581 assessment is Final Approved the CoF form becomes read-only.
Doing a Simple Consequence of Failure (CoF) Assessment
Detailed RBI 581 CoF assessments are comprehensive but can be time‑intensive. You can also do a Simple CoF Assessment. This is a faster alternative by allowing you to manually define key consequence values, while still keeping the full detailed assessment available when needed. This is particularly useful when CoF values are calculated using external tools and must be entered quickly.
To do a Simple CoF Assessment:
Go to the Consequence of Failure Tab.
Click the blue Detailed toggle in the top right to switch to the Simple CoF assessment.
The Indicator will now show a yellow Simple toggle. To switch back to the Detailed assessment you can click Simple.
Click Edit.
Enter the Area Consequence and Economic Consequence.
Click Save.
After saving, these values are used to determine the corresponding consequence categories and to calculate risk using the same logic applied in the Detailed method.
You can switch at any time between the Simple and Detailed assessment without losing data. The most recently calculated assessment automatically becomes the active one.
You can filter on the Detailed or Simple CoF Method via the RBI 581 Main Screen.
Bulk Importing Simple Consequence of Failure data
It is possible to do a bulk import of Simple CoF data via Setting\Data Transfer\Import Data. During import, the provided Area and Economic Consequence values are used to determine the corresponding consequence categories and to calculate risk using the same logic as in the Detailed method. The Consequence of Failure Method for the updated analyses is automatically set to Simple.
If a Probability of Failure (PoF) calculation already exists for the analysis, IMS will automatically trigger the MII calculation once the import is complete.