The mission of the maintenance department is to ensure the plant’s assets remain operational. We buy an asset to provide some value to the owner. Maintenance ensures that the value. The value derived comes from the asset’s use. Maintenance also manages the asset’s ownership risk.
These two functions, ensuring we get the value of the asset and managing the risk of ownership, are the core of Asset Management and the mission of maintenance.
Without maintenance, asset management cannot deliver value or control risk.
Asset Management is the overall approach of an organization toward the assets it needs to fulfill its mission. It is a broader field than just maintenance. Asset Management includes defining the business case for the asset, engineering it, building it, or purchasing it. Once the asset is ready, it includes installation, commissioning, operation, and maintenance. Finally, it includes responsible retirement and disposal. Asset Management is defined by ISO 55000 and related standards.
The laws of entropy rule the universe. Entropy means (for our purposes) that everything will decay, run down, or become disorganized and useless. Our assets will inevitably go from operational to non-operational. Just like the stars in the sky, everything will wind down. They will eventually run out of fuel, and (after a trillion years or so), the universe will reach high entropy (highly disordered and unable to do anything useful). Kind of a state of white noise. The destruction of every asset follows the law of entropy.
Of course, what happens in a trillion years is not our problem. The mission of the entire maintenance effort is to keep deterioration (entropy) at bay so we can deliver value to our company while managing the risks it entails.
How Failure Actually Begins and Progresses
Entropy is the macro view of maintenance. If we zoom in on a micro-level breakdown, we need to understand how things fail. Once we know these modes, we can design procedures that detect these problems, prevent failure, or extend the machine’s life. We call this Preventive Maintenance.
The basic idea is that an element of a machine operates at a particular performance until something happens. For each failure, there is a precipitating critical event (CE) that sets in motion the cascade of events leading to failure. could be damage, contamination, heating, overloading, corrosion, and even operational abuse.
This event, the “something,” can be microscopic (maybe even molecular). It could be dirt falling into a bearing or a fatigue micro-crack. It could be almost anything that results in a loss of performance. Over time, the defect grows and performance declines. The slope and the deterioration rate depend on the engineering situation. The shapes of the curves for different elements are similar, even though the scales differ radically.
The earliest failure signals are microscopic, not dramatic.
The curve that defines this is called the performance–failure (PF) curve. Typically, the decline in performance (the slope of the curve) starts slowly and then accelerates. This means there may be little or no discernible decline in performance at the outset (near the precipitating event). However, over time, the performance declines rapidly. There are many great articles on the PF curve (reference URLs)
Designing for Reliability Before Operations Begin
From Asset Management, we know that the key to a good maintenance program is the design and construction of facilities that follow RAMS (Reliability, Availability, Maintainability, and Safety) practices.
Well-designed, built, and installed equipment considers maintenance needs to ensure reliable utilities and adequate workspace. To be successful in the operational and maintenance phase, it is essential to develop a simple, practical maintenance strategy and cultivate a skilled, knowledgeable maintenance organization.
Safety is an essential function of any maintenance program and should be considered alongside personnel, nearby communities, and the environment. Energy conservation and controlled costs are part of successful maintenance management.
A well-organized and managed maintenance program contributes to profitability, reduces operating costs, and increases productivity.
Choosing the Right Maintenance Strategy
We have several strategies to achieve that mission. We can, for example, wait until the equipment breaks and fix or replace it. This is called Run-To-Failure (RTF). It is by far the most popular strategy when the risks of failure are not too dangerous or costly. Mainline equipment in a chemical plant, for example, cannot afford to adopt a run-to-failure strategy because of the risks to safety, downtime, and repair costs. RTF is still popular with ancillary equipment.
Preventive maintenance exists to manage failure before it manages you.
Another strategy is a predictive and preventive maintenance (PPM) program. Periodic service and inspection help prevent or postpone machine breakdowns and alert us to physical signs of deterioration. The period of the services can be driven by the calendar (easiest), run hours (second easiest), or utilization, such as tonnage, barrels, etc. (hardest but most accurate). In some facilities, all three are used to schedule service.
A third strategy is to add sensors to all equipment that report, in real time, conditions inside the asset. Using sophisticated algorithms (a combination of many individual checks on the collected data), the plant can be run efficiently. Combined with AI, much of the growth in maintenance management is in this domain.
You will find that the best overall strategy will be a combination of all three approaches.
How Maintenance Decisions Should Be Made
There should be one overriding idea that drives decisions about assets, maintenance, and scheduling. The idea is to make decisions from the perspective of what is best for the whole company. Fights between maintenance and production are entirely legitimate and even helpful. Different groups have different priorities. The bottom line is that the best decision is the one that benefits the company the most over the long term.
Aligning Maintenance Schedules With Production Demands
Factories are built to manufacture products in a particular quantity and quality. Extensive resources are dedicated to the design and development of systems and procedures to ensure that the plant’s material requirements plan (MRP) consists of the following three elements:
- Equipment Custody (control) in good working order and up to specifications
- Bill of Materials (all the resources such as raw materials, specialized tooling, and consumables)
- Labor with the requisite competencies
Good maintenance programs and practices should be part of the MRP to ensure consistent performance without interruption. The maintenance management effort is responsible for securing adequate resources to study, understand, and optimize the maintenance process.
