Page 608 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 1 2.1 Implementation and Communication Best Practices

Total repair hours*
MTTR =
Number of repair events
*includes corrective maintenance time
(actual labor hours as a result of design modifications)

Fig 12.1.10 Mean time to repair
expressed in local currency. At this point, note the amount of
daily revenue from a process unit in your plant in Figure 12.1.11.
Note that amounts can vary from $100,000 to over $5,000,000
per day depending on the process and the size of the unit.
If a critical equipment unit suffers a forced outage or is out of
service due to poor maintainability (extended repair time), the
product revenue shown in Figure 12.1.11 will be lost for each
day the critical equipment unit remains out of service. There-
fore, the cost of unavailability is the total of the values shown in
Figure 12.1.12.
The cost of unavailability can be a powerful tool to use in
preparing reliability improvement plans.
Fig 12.1.13 The Reliability Pyramid

Date: ________________
1. Clearly stating impact of problem on plant profit (cost of
Amount: ________________ unavailability)
Process unit type: ________________
2. Preparing a brief statement of:
Problem
Impact on plant
Fig 12.1.11 Daily product revenue for a process unit
Reliability improvement plan
3. Being confident!
4. Being professional
5. Being autonomous (do not expect management todoy our job!!)
Lost product revenue × days forced outage 6. Providing timely updates
Maintenance costs
Replacement part cost
Labor cost Fig 12.1.14 Obtain and maintain management support by the
Unnecessary turnaround time* above
*Assumes process unit start-up is delayed by activity
items are not taken into account, the accuracy of the conclusions
reached during the assessment phase will be significantly reduced.
Fig 12.1.12 The cost of unavailability critical rotating equipment In my experience, most failures in predictive maintenance
(per year) and troubleshooting exercises occur because the entire system
in which the component operates is not considered. Every
Optimizing reliability component in every piece of machinery operates in a system.
Defining the system and all of the components contained
The key to reliability improvement is to build a solid program therein is a very important step in successful problem analysis.
foundation. Figure 12.1.13 shows the reliability pyramid. Refer to Figure 12.1.17.
The success or failure of any reliability improvement program
directly depends on obtaining and maintaining management Experience counts!
support. Figure 12.1.14 presents guidelines for meeting this Having experienced analysts to determine the root causes of low
important objective.
reliability is the next step in building a strong program.
Input data
Once management support is obtained, input data forms the Include all the facts (operation, reliability, maintenance failure
foundation of the program. Figure 12.1.15 presents important analysis, etc.)
guidelines concerning input data. Consider the machinery environment
The environment or surroundings for any piece of rotating Consider the entire system
equipment play an important part in determining the availability Only use proven data (don't guess!)
Accuracy is most important – confirm data is correct
of that particular item (refer to Figure 12.1.16).
This figure shows that the rotating equipment environment is
the process unit in which the equipment is installed. If any of these Fig 12.1.15 Reliability input data

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