RBI Results
After you have entered all of the component data, you can calculate the results by choosing System Hierarchy > Risk Based Inspection > Calculate Risk.
The Calculations Options window will appear, allowing you to select which components to calculate.
If you select Ignore incomplete components, the software will not attempt to calculate the results for components that do not have all of their RBI properties defined. If not selected, RBI will validate all components before calculating the results and will stop validation on the incomplete component and not calculate the results for any component.
If you select the Set reliability policy to 'Based on RBI Analysis' check box, the software will use the model created from the RBI results as the reliability policy on the Properties tab of the Analysis panel.
Calculated Results
Area and Financial Consequence Results:
Area Consequence Results displays the estimated effect of a failure based on safety.
Financial Consequence Results displays the estimated monetary effect of a failure (i.e., the repair, clean-up, replacement and other costs).
RBI Date Results displays results on the date the results were calculated:
Overall Damage Factor and Probability of Failure displays the total damage factor associated with the component as well as the probability of failure associated with the total damage factor.
Risk Analysis (Area) displays the calculated area at risk and the probability category and consequence category of the component failing (as based on the Risk Category values for the project) at the given date. It also displays the calculated Risk Priority value based on the scoring matrix (i.e., Low, Medium, Medium High or High).
Risk Analysis (Financial) displays similar information for the financial consequences of failure.
Plan Date Results displays the same type of results as the RBI Date Results node, but shows the risk values on the plan date (i.e., the date of the planned maintenance) assuming you do nothing until then.
If the analysis indicates that an inspection is required before the plan date, the Target Date Results node specifies the target date and provides information about when you should inspect the component and the anticipated state of the component on that date.
If the risk on the plan date is less than the maximum acceptable risk, then no target date is given as no inspections are needed until the plan date.
Recommended Inspection(s): If applicable, this node displays the number of inspections needed for each type of damage and the level of inspection that you will need to perform on the target date when you inspect the component to get your desired results.
While the exact meaning of effectiveness varies depending on the component and what its properties are, the following table shows a generic version of the inspection levels that can be recommended to be performed.
Level |
Generic Meaning |
A |
Highly Effective |
B |
Usually Effective |
C |
Fairly Effective |
D |
Poorly Effective |
E |
Ineffective |
Plan Date with Inspection Results displays the same type of results as the RBI Date Results node, but shows the risk values on the plan date assuming that the recommended inspections on the target date are carried out. If no inspections are needed, the node states that.
Generated URDs
If you select the Set reliability policy to 'Based on RBI Analysis' check box when calculating RBI results, the software will generate a URD based on the RBI analysis results. In this case, the failure model is always a 2-parameter Weibull with the time units set to Years. These models cannot be directly modified by any user. To change them, you must change the analysis and recalculate the model.
If you already have an existing model for the component, you can clear the Set reliability policy to 'Based on RBI Analysis' check box and base the reliability on it instead. (In other words, the model generated by the RBI software is best used in cases where you do not already have an established reliability model.)
Models are not created for pressure relief devices (PRDs), which are replaced either at the date the maximum acceptable risk is reached or when the plan date is reached, whichever is sooner.
Generating Scheduled Tasks
When the URD is created, the software also creates a scheduled task for the component:
For non-HEXTUBE components:
If inspections are needed, then an inspection task is created and scheduled for the date given in the Target Date Results node on the Results tab.
If inspections are not needed, then a preventive task is created, scheduled for the plan date.
For HEXTUBE components:
If no life extension will be performed, then an inspection task is created.
If life extension will be performed, then a preventive task is created.
The task is scheduled for the target date, if it exists. Otherwise, the task is scheduled for the plan date.
Using the Generated URD in Other Analyses
The generated URD and model can be used in many places in your analyses. For example:
You can use it with a Functional Failure Analysis (FFA) to generate the maintenance tasks for the component.
You can use it in the Failure Modes and Reliability Analysis (FMRA) to determine the reliability of the entire system (including synchronizing the hierarchy with BlockSim) or calculate the system availability and cost values.
You can use it when performing simulations and cost calculations.