It’s easy to assume reliability centred maintenance is risk-based maintenance. After all, we associate higher risks with less reliability! Likewise, it’s also quite easy to mistake risk-based maintenance, which reduces risk, for a reliability centred approach. Too confusing? Don’t worry! We’ll explain it all in one article.
What is reliability centred maintenance?
Reliability centred maintenance (RCM) is a method to identify problems that compromise functionality. First, it analyses breakdowns to assess how reliable an asset is. Then, it systematically studies how each failure compromises functionality, why they happen, their consequences, and how to prevent or predict them. The assessment criteria is generally known as the 7 Questions of RCM.
After that careful analysis, it devises a plan to tackle critical issues and produce at maximum capacity. However, it should not be mistaken for a “preventive maintenance plan”. RCM is more incisive, because it looks at individual assets and their failure modes before scheduling maintenance work orders.
The result is greater reliability and increased productivity. Of course, companies also avoid unnecessary maintenance, breakdowns and expensive repairs, which reduces overall maintenance costs. As you can imagine, it is applied across several industries, including in the food industry, oil and gas industries, manufacturing and even at amusement parks.
What is risk-based maintenance?
Risk-based maintenance (RbM), as the name indicates, prioritises assets according to the risk they carry. It starts with a risk assessment, based on the probability of failure and the consequences of failure. Both are aligned in a criticality matrix to determine which assets pose the most risk.
That risk assessment is what guides the maintenance plan. It allocates human resources, money and parts to assets that pose the most risk. Lower-risk assets have more flexible plans that change according to what budget and time allow. Overall, it minimises the risk in the most cost-effective way.
This strategy protects employees and those who use the facilities, extends the useful life of critical assets and eliminates low-value tasks. Just like RCM, it’s used in asset-heavy industries. However, because it establishes clear priorities, it might be adopted by managers that have limited resources for their maintenance plan.
Differences between Reliability Centred Maintenance and Risk-Based Maintenance
By now, it must be clear that RCM and RbM, although somewhat related, are not the same thing. Let’s take a closer look at the differences between reliability centred maintenance and risk-based maintenance.
Risk-based maintenance prioritises risk. Reliability centred maintenance, on the other hand, prioritises functionality. Even though “risk” and “productivity” can overlap, they are not the same. The reduction of risk enhances reliability, but the reverse is not true. An asset’s output might improve without eliminating potential hazards.
Think about an air conditioner, for example.You can retrofit it to make it more reliable, but it doesn’t necessarily reduce risks. Likewise, replacing an air compressor on an asset will likely improve its output, but the risk (a leak, for example) remains the same. Therefore, as we’re beginning to see, RbM and RCM don’t always prioritise the same equipment.
The starting point
Those different priorities mean the starting point of each one is also different. RbM evaluates all the assets, and then decides which ones take priority. We reach less critical assets little by little. In a sense, it’s like a vaccination campaign. There is a limited amount of vaccines; there are groups at higher risk. The roll-out starts with those groups. Later, if more vaccines become available, other groups qualify.
RCM starts from a smaller inventory. It focuses on assets whose function is absolutely vital – their failure will halt production. That’s why it is so popular in factories and plants. If we continue with our vaccination campaign allegory, we wouldn’t look at risk groups straight out of the gate. Instead, we would think “who do we absolutely need to protect?” and vaccines would probably be given to key people, such as the president or the monarch.
Obviously, there is one group both RbM and RCM would protect: healthcare workers. In the first case, we can consider they are at higher risk because of their job. In the second one, they are essential assets. Besides, note that one preventive measure (the vaccine) is not incompatible with condition monitoring techniques (testing, creating a ‘bubble’ around strategic “assets”, and so on). Managers decide what works better for whom.
Strategic thinking vs. methodical approach
Risk-based maintenance is a strategic choice. You have limited resources for maintenance and repairs, so you choose to eliminate the biggest risks. Reliability centred maintenance does not pose a question of “either…or”. Facility and maintenance managers don’t necessarily adopt RCM due to a lack of resources, but because they need to increase productivity at their plants.
It consistently asks “what’s the best maintenance method to preserve each asset’s function?”. Should we monitor its condition, inspect it periodically, or wait until it breaks? Which is more effective? To find an answer, it takes 7 questions, always in the same order. It’s a methodical approach.
That’s where the similarities begin. To decide the optimal methods to preserve function, reliability specialists look into equipment failures, the criticality matrix, and which parts they require. The criticality matrix is, of course, also heavily featured in the RbM decision-making process.
So, which one is better?
None is better than the other. Risk-based decisions are strategic. Reliability centred decisions are tactical, to maximise the reliability assets and achieve the company’s goals. Whether you choose one or the other depends on the available resources, the asset portfolio you’re dealing with, and your company’s objectives.
Either way, one thing is for sure: you need to look into asset history and logs to take action. Schedule a demo and learn how you can organise maintenance logs, monitor KPIs and improve your operations with an IMMP.