The semi quantitative risk assessment provides a great level of analytical detail on the damage mechanisms that may be noted and defines the consequence of failure in terms of affected areas combined with an assessment of the generic failure frequency that may be observed. Like the qualitative assessment the semi quantitative Overall Risk Rating Summary (Risk Category) is derived by the system from the combination of the Overall Probability of Failure (POF Category) and the Overall Consequence of Failure (COF Category).
Consequence of Failure
The Consequence of an Equipment Failure shall be assessed in four Categories:
- Consequence to People - Safety
- Consequence to Environment
- Consequence to Asset - Damage Cost/Production Loss
- Consequence to Reputation
- Assessment of Consequence of Failure will require the assistance from Customer's Operations, Maintenance and other personnel
Probability of Failure
Equipment Historical Inspection data and, where available, Repair History will be entered into the application. Evaluation of the data will be carried out by the Reliability Engineer and RBI Specialist. The application will, based on available data, determine the Component Corrosion Rate and Remaining Life for insertion into the Probability of Failure screen. The Failure Mechanisms associated with the equipment will be reviewed and displayed on the POF screen. Probability of Failure is by the factor of failure mechanism, factor by current inspection effectiveness, remaining life and other parameters depending on the type of equipments used.
Based on the Consequence and Probability of Failure the resultant Risk shall be identified and displayed on a 5x5 Risk Matrix. At the same time the Asset Hierarchy will also be color coded to display the level of Risk for each piece of equipment.