Step 12 Evaluate the Maintenance Scenarios (Civil)

In addition to defining an Inspection Plan for your Civil Equipment, you can also use IMS to define Maintenance Scenarios. Your first step should be to define a number of alternative scenarios, and then estimate the Life Cycle Cost (LCC). Lastly you need to evaluate the Scenarios.

Methodology

Compare Total Life Cycle Cost

The key question here is: “Which PM plan is the most cost-effective over the Life Cycle period considered?”

After the cost profile has been prepared it is rather straightforward to determine the cumulative cost in the Life Cycle Year. The plan that has the lowest cumulative cost should generally be the most cost-effective plan. Other factors than costs are not considered by this economic evaluation. These factors are for instance the required (management) attention, workload of the personnel, plant logistics. It is however strongly recommended to also consider these factors in the decision-making process.

The year of maintenance planning is the year that the study is conducted. The life cycle year is the horizon over which the various scenarios should be compared.

Evaluate Value Investment Ratio

The effectiveness of the investment of money in the Preventive Maintenance strategy can be measured by calculating the Value Investment Ratio (VIR), which in its simplest form is defined as follows:

In principle, when the VIR is greater than 1 it is expected that it is more effective to execute the PM plan than letting the asset run to failure. In practice a higher threshold value can be used before it is decided to execute the PM plan. This applicable threshold value should be established in agreement with plant management.

Software

Comparing Base Case and Maintenance Scenarios

To compare the Base Case and the other Maintenance Scenarios:

• Select the Cases tab.
• Compare the Life Cycle Cost (LCCosts).
• Compare the Value Investment Ratios (VIR).

Compare LCCost and VIR.

Select Optimum Maintenance Scenario

• Identify the Scenario with the highest VIR (thus minimum LCCost).
• Select the Overview tab and click Edit.
• Select the Scenario you identified from the pull down menu.

Select a Scenario.