Process Technical Services (PTS) can help develop a preventive maintenance program that will effectively reduce plant operating cost relative to use of corrective maintenance programs that wait until a failure occurs. Modern technology has produced tools and techniques that can differentiate between those elements in a process that should be included in a preventive maintenance program from those that should not.
Preventive maintenance is a schedule of planned maintenance activities designed to prevent breakdowns and failures while in service. The primary goal of preventive maintenance is to replace equipment before it actually fails to preserve and enhance the reliability of the process.
Preventive maintenance involves routine equipment checks for wear, partial or complete overhauls at regular intervals, oil changes, lubrication, bolt tightening, and many other checks. With a regular schedule for checking equipment, records of equipment deterioration can identify worn parts that can be replaced before they cause system failure. Modern inspection and diagnostic tools can enable accurate and effective measurements of equipment deterioration.
A preventive maintenance program should be integrated into the normal schedule of semi-annual, annual, and biennial shutdowns for major maintenance work on the plant. Some elements of a preventive maintenance program can be managed without interruption to the production schedule, and these pose no problem. Other elements in the preventive maintenance program can only be accommodated by partial or complete shutdown of production operations. These items may influence the schedule for major shutdowns, but are not normally the dominant factor in the decision to shut down.
One misconception regarding preventive maintenance is that it is more costly than other maintenance programs, such as the run to failure approach. This may be true in some cases. However, a correct comparison should consider both the immediate costs and the long term costs and benefits. Both the cost of lost production time from unscheduled equipment breakdowns and the benefits from an increase in the effective system service life need to be incorporated into the evaluation.
Preventive maintenance is a logical choice only if both of-the following two conditions are met:
- Condition #1: The component in question has an increasing failure rate. In other words, the failure rate of the component increases with time, thus implying wear-out. Preventive maintenance of a component that is assumed to have a constant failure rate does not make sense.
- Condition #2: The overall cost of the preventive maintenance action must be less than the overall cost of the corrective action approach over an extended period of time.
If both of these conditions are met, then preventive maintenance makes sense.
However, there are often several components in a preventive maintenance program with different optimum replacement times. If repair or replacement of these components requires a significant interruption to the production schedule, then components should be grouped and an optimum time determined for the group. This approach provides an improved opportunity to influence the schedule of major shutdowns, which are determined by a number of factors other than the requirements of a preventive maintenance program.
Process Technical Services has personnel experienced in setting up and managing preventive maintenance programs that can be smoothly integrated into the decision process surrounding the timing of plant shutdowns for maintenance work.