STEP 6 & 7: Define the Risk Number and Risk threshold

After filling in all failure data, it is time to have a look at risks. Risk is indicated by means of a Risk Number. This number is the product of the weighting factors of the MTTF, repair duration and classification of an effect. Whenever a risk exceeds the set threshold, the risk threshold, the part in question will be considered critical. Calculating risk numbers is done automatically by Asset Strategy Optimization. The results of these calculations are visualized in the risk matrix. The following topic will describe the risk matrix in more detail. In some occasions it may be desirable not to consider weighting factors of repair duration in the calculation of the risk number. This, too, will be explained below.

Note: The risk matrix is explained in detail in the topic Risk Matrix.

Risk Matrix

The screen shot below shows the risk matrix, related to one business objective. Choosing a different business objective is done using the drop-down menu called “Business Objective”.

Example of a Risk Matrix

The top line of the matrix shows the classifications of the MTTF. The second row shows the classifications of the repair duration, which are repeated for each MTTF classification. The column on the left shows the classifications of the business objectives. The matrix cells show risk numbers, as a column of three. The topmost number is the risk number. The middle number indicates the number of combinations of a failure mode, failure cause and failure condition, that end up in this cell as a result of the risk calculation. The lower number indicates the number of combinations of a failure mode, failure cause and condition that end up in this cell as a result of the risk calculation performed in a chosen scenario (if any). If no scenario is defined, this number is zero. Working with Simulation and scenarios FL21 is part of the chapter on simulation and is not explained here.

The risk thresholds are filled in the field Risk Threshold at the top left of the matrix. By pressing the "refresh-button" , next to the veld, the risk matrix is recalculated. The combined classifications of which the calculated risk number exceeds the risk threshold will be colored in red (with a white font type). The non-critical classifications will be colored in green with black letters.

Note: Working with scenarios is explained in detail in topic Simulation and scenarios.

The bottom of the risk matrix screen shows an overview of the total of failure causes of the current system, for the chosen business objectives, that are under or above the threshold. The bottom row indicates the same numbers but based on results from executing a scenario (chosen at the top of the matrix screen).

As discussed in the introduction, it is possible to choose whether or not to take the repair duration into account, using the field Downtime in Risk Analysis.

Note: Changing the value of the field Downtime in Risk Analysis will not be saved here. To make the value persistent, it should be changed in the screen Business Objectives.

Reports

The report Risk Analysis gives an overview of the failure modes and effects per Part, the risk thresholds per business objective and the relevant failure data such as failure cause and condition, with its corresponding risk number. The parts are sorted on the Tag number.