Preventive maintenance is essential in ensuring the longevity of equipment in any industry. It involves regular inspections, testing, and maintenance of equipment to detect and prevent potential problems before they occur.
A modern preventive maintenance program should adhere to certain principles to be effective. In this blog article, we will discuss the 9 principles of a modern preventive maintenance program.
Understanding and implementing these principles will help you minimize the impact of failures and maximize equipment uptime, which ultimately leads to cost savings, increased productivity, and safety.
Principle #1: Not all failures can be prevented.
Preventive maintenance cannot prevent all types of failures. A good maintenance program should accept that some level of failure will occur and be prepared to deal with them. Rather than trying to prevent all failures, it should focus on identifying and mitigating the most critical ones and accepting low-impact failures.
Principle #2: Most failures are not age-related
Research by the airline industry and the United States Navy has shown that most equipment failures are not related to the age of the equipment. This suggests that for most equipment, time-based maintenance tasks are not effective in reducing the likelihood of failure.
Yet despite this, most maintenance tasks out there are still time-based. That’s why it’s important to choose the right type of maintenance that matches your failure mode instead of automatically going with time-based maintenance tasks.
Principle #3: Not all failures are created equally.
Not all failures have the same consequence, even if they relate to the same type of equipment. For example, a leaking tank may have severe consequences if it contains a highly flammable liquid, but if it is full of potable water, the consequences may not be as significant.
A good maintenance program should consider both the consequence and likelihood of failures and use the concept of risk to determine where to allocate resources for the greatest benefit. This approach helps to get the biggest return on investment.
Principle #4: Parts might wear out, but your equipment breaks down
Simple components often provide early signals of potential failure if you know where to look, so tasks can be designed to detect and act on potential failure early on.
However, when it comes to complex equipment made of many “simple” components, the situation is different. Complex equipment has many varied failure modes, and their failures do not tend to be a function of age but occur randomly.
Principle #5: Hidden failures must be found
Hidden failures are failures that remain undetected during normal operation and only become evident when the equipment is needed or when a test is conducted to reveal the failure. They are often associated with equipment with protective functions such as high-pressure trips.
Failure-finding tasks should be conducted on equipment with protective functions to find and fix hidden failures before the equipment is needed to operate. Failure-finding tasks do not prevent failure instead, they seek to find and reveal failures that have already occurred but have not been identified yet.
Principle #6: Identical equipment does not mean identical maintenance
Just because two pieces of equipment are the same, it doesn’t mean they require the same maintenance. In fact, they may require completely different maintenance tasks.
A classic example is two identical pumps in a duty-standby setup. Both pumps process the same fluid under the same operating conditions, but one is the duty pump, and the other is the standby.
The standby pump might have a hidden failure mode which will only be revealed when the duty pump fails. This failure mode requires a failure-finding task, which is not needed by the duty pump.
Principle #7: You can’t maintain your way to reliability
If the equipment has poor inherent reliability or performance, doing more maintenance will not help. No amount of maintenance can raise the inherent reliability of a poor design. The most effective approach is to ensure that the design is correct from the start, but even the most proactive plants have design defects. This is why the most reliable plants have an effective defect elimination program in place.
Principle #8: Good maintenance programs are efficient
It’s common to find tasks in PM programs that add no value and waste resources. So, it’s important to remove unnecessary maintenance from the system, have a clear and legitimate reason for every task in the maintenance program, and link tasks to dominant failure modes. This allows for the prioritization of tasks in a resource-constrained environment.
Principle #9: Good maintenance programs continuously improve
The most effective maintenance programs are always evolving and improving, making better use of resources and becoming more effective in preventing failures that matter to the business. When looking to improve a maintenance program, it’s important to understand that not all improvements have the same impact.
Final Thoughts
A modern preventive maintenance program should adhere to the principles outlined above to ensure the reliability and longevity of equipment and machinery. By accepting failures, focusing on underlying causes, and continuously improving, a preventive maintenance program can minimize the impact of failures and maximize equipment uptime.
