To choose maintenance techniques at the plant; success stories, experiences, and historical data are one source for choosing maintenance strategy. Such as: the implementation of vehicle maintenance every 5000 hours. Manufacturers believe it to be an approach based on historical data. This approach is often done in plant in implementing out scheduled maintenance. Then, the identification of specific indications / symptom of each failure mode on the plant engine, the techniques and tools were explored to predict engine failure.
In general, to check asset conditions has been carried out with predictive technology. For example: Machine A vibration data shows that the vibration level is close to the C value limit based on ISO 10816, the engine condition is deteriorated. Engine B vibration data shows the level already at D value based on manufacturing configuration, so the condition is very bad. From the two data, the maintenance section will choose which equipment will be repaired first. This example can easily be compared if there are only two data possessed. If we have a lot of data, the maintenance team will be difficult to prioritize the repair work.
RiBM uses information from conditions of failure and consequences that will occur. Risk analysis is a technique to identify, classify, quantify and evaluate losses that will occur due to failure. Risk analysis (Figure 1) combines the identification of failure and detection failure. Identification of failure maps failure and consequences that will occur. Failure detection predicts the possibility of failure. So that we can find out how much the possibility of a failure that creates consequences.
Figure 1. Risk Analyzing Cycle
The result of failure risk calculation is a consequence in numeric units (money). Parameters that can be assessed in units of money are production loss, equipment replacement, service used and fines (if any) if a failure occurs. It can be assumed as a worst-case scenario. Risk is most likely to occur with a very large money usually occurs when the operating period ends (Mean Time to Failure). Risk calculation uses an exponential approach (Figure 2).
Figure 2. Risk Curve
By making risk in the form of value for money, we can:
- Assess current risks;
- Predict future risks;
- Compare the value of the risks that can occur and the maintenance cost that spent, and;
- Prioritize maintenance work based on the risks that will be managed.