by Carlos Mario Perez Jaramillo
RCM is the most effective, quick and cost-effective methodology for defining maintenance plans for assets, but today, many organizations are dedicated to creating excuses on why not to implement this method and have instead blamed RCM, creating a series of myths. The time spent in making excuses could instead be invested in successfully executing RCM.
The aim of this article is to refute the most common myths about RCM, with the assumption that any organization that has successfully applied this methodology has not identified any negative aspects and has received only the benefits of proper implementation.
MYTH 1:RCM means reliability centered maintenance because it helps to improve mean time between failures (MTBF).
The word reliability in RCM refers to a series of concepts, attributes and demands that together allow an organization to feel satisfied with its performance.
The most known concept to define reliability is: “The probability that an equipment or system operates without failure for a certain period of time under operation conditions previously established.”
However, the concept is sometimes used in the wrong way because of the interpretation given to the word “failure.” For many, failure means it just stops, so they build complex mathematical models to calculate the probability of stops without taking into account that there are also fails when it is unsafe, inefficient, expensive, or has high levels of rejections and contributions to a bad image.
For others, “reliability” is a set of theories and mathematical methods, operational practices and organizational procedures that, applying the study of the laws of occurrence of failures, can be directed towards the resolution of the problems of forecast, estimation and optimization of the probability of survival, improvement, average and percentage of time of functioning a system.
A very common argument is whether or not reliability is a statistical problem. The answer to this argument is that data management has an undeniable usefulness in the management of companies. It is necessary to distinguish whether the statistic is used to handle real data, view behavior, or support predictions and estimates that sometimes border on daring and irresponsible speculation.
MYTH 2:RCM solves all reliability problems of a company.
Going back to the concept of reliability as the average time between occurrences of failures, it must be remembered that it is an average number. There is a big difference between probability and reality, which creates a lot of confusion. A probable failure is a possible failure; when a failure took place, it is a real failure and not necessarily a calculation algorithm that guarantees its occurrence at a particular time.
The objective of RCM is very clear: define the most proper maintenance to ensure that assets meet functions required by its users. However, its rigorous and appropriate installation is useless if it is not conjugated to engage with other initiatives, activities, functions, methods, tools and methodologies that, when timely and correctly applied, provide the levels of reliability required.
These are some points that must be met in implementing RCM methodology, which will lead to great benefits. However, this does not mean that it will solve all reliability problems of the company.
Currently, there are tons of concepts and maintenance techniques, and more approaches emerge often in a permanent dynamic.
MYTH 3:There will be no more failures after applying RCM.
If having no failures is an ideal and desired state, and for many, reliability equals zero failures, then there is no method or methodology that avoids and/or reduces all failures or risks.
The RCM objective is to achieve more reliable assets and this is accomplished if they fail less, if failures last for less time, if there are fewer shutdowns lasting for less time, if risks are diminished, if they look better, if the nonconforming product is reduced and if the cost of operation is decreased.
A correctly elaborated and rigorously applied RCM analysis greatly reduces failure probabilities, the number of failures, risks and duration of non-desired events, in addition to providing best elements to be prepared if any component fails. Any combination of the above makes a more reliable asset.
Failure modes can be missed during the analysis and, therefore, periodic review of assets allows continuously improving quality. This explains why it is heard in some organizations that “equipment has failed, therefore RCM is wrong.” This statement is totally groundless since if a defined failure management strategy for some modes has been leading to failure, therefore failures may occur.
RCM itself, as a concept, does not assure suitability of the analysis. It requires common sense, honesty and validity of those who make decisions.
MYTH 4:A probability curve defines if RCM is applicable.
RCM is defined as a process to determine the proper maintenance, the correct way to run it and the right opportunity to apply it. It is a process suitable for any type of asset, anytime and in any organization. Interpreting the famous “bathtub curve” for an entire asset according to a probability curve factor form and defining that a methodology applies only to a part of the curve or to a part of its operational life is a great mistake since this implies that RCM analysis considers only certain failures and characteristics.
If RCM analysis is well done, there will be failure causes due to human mistakes, influences of the environment, deterioration by normal use and wrong design practices. In addition, there will be appropriate failure management strategies for each of them through their operating life.
MYTH 5:Application of RCM should start from the current maintenance plan.
RCM is a zero-based analysis. This means the analysis is performed as if maintenance, which includes operational inspections, will not take place. As a result, the new maintenance plan is not biased by current practices that may not be technically appropriate.
In fact, the most popular method for “shortening” a RCM process begins with the current maintenance work. Users of this approach try to identify the failure mode that each task is meant to prevent and then work forward through the last three steps of the RCM decision process to reassess the impact of each failure mode and identify a more effective failure management strategy. This approach is also known as “reverse RCM.”
This approach is disadvantageous because it is assumed that current maintenance plans cover all failure modes that reasonably require any maintenance. However, properly applied RCM generally shows that failure modes that really require a maintenance strategy are not covered by the current work in this area.
Retroactive approaches are especially weak when specifying proper maintenance for protection devices. This explains why most protective devices are kept in a deficient manner, or no maintenance is performed on them. So in most cases, a large number of protection devices will continue to receive no attention, since tasks were not specified for them in the past.
MYTH 6:A criticality analysis must be applied before RCM analysis.
An RCM analysis does not require a previous criticality analysis, which is recommended by some to choose assets to be analyzed. Criticality is the name given to the feature that allows establishment of a classification or hierarchy within a group of systems and assets according to a criterion. It aims at facilitating decision making by directing efforts and resources in areas where they are more important or necessary.
Criticality analyses normally can be made at asset level and the deepest ones at component level. But despite their goal, they are insufficient in defining the impact of a possible failure since components have many ways of failing and their structural analysis is insufficient, if lacking functional consideration. While some have factors intended to express concepts associated to affectations in the organization, sometimes they do not include human mistakes and environmental influences in the failure manner.
Frequently, seemingly superfluous assets are responsible for incorporating items that are very important in terms of safety and/or environmental integrity.
It is right to define priorities in order to run the analysis, but it should be looked at carefully whether to spend months of work and a lot of man-hours to make the classifications offer some benefit. Normally, those who lead organizations or operate and maintain them have sufficient criteria to know what dissatisfies them and that is reason enough to decide to run an analysis.
MYTH 7:It is hard to define systems and functions in RCM.
This is a groundless objection since an operator who knows an asset or those who have maintained it have no problem defining what they want it to perform. In fact, they understand it and know exactly what they expect from its operation.
Preparation of hierarchy diagrams, support from other maintenance tools and asset taxonomy, combined with proper application of the maintenance information system, allow for an understanding of what they are expected to do and selecting appropriate levels.
MYTH 8:RCA replaces RCM; failure analysis performed to find the root cause (RCA) replaces RCM analysis.
Failure is defined as the inability of a component, equipment, asset, or system to perform its function as specified, or an inability of a system or component to perform a function within specified limits.
Root cause analysis (RCA) is defined as a process to find the root causes and propose actions for each upon occurrence of a failure.
Under this assumption, there is a root cause to identify each time an event takes place and proposals are made when the failure occurs. This is the backbone of a reactive asset management strategy, which could be expressed in a concise manner like, “analyzing upon failing.” It sounds good at the beginning, but under this point of view, the strategies all remain “waiting” for failures to occur.
Experience has shown that there is no single root cause for a failure; there may be several and all. But with different occurrence probabilities, orientation towards a possible fault is reactive and only serves to improve the performance of the work and not make the equipment more reliable.
RCM orientation is totally different. It seeks to anticipate the occurrence of failures, or failing that, have defined strategies if they occur. The real RCM proactive approach seeks to actually apply the plan, do, check, act (PDCA) cycle throughout the asset’s lifecycle.
MYTH 9:RCM favors condition tasks at the expense of preventive maintenance.
RCM is a rigorous process to select the best type of asset maintenance. The correct application of the method ensures reaching appropriate conclusions without favoring any kind of maintenance. Rarely is there a relationship between equipment reliability and age, however, many failures give an indication or sign that a failure is occurring. When finding these faults in this state of “potential” failure, it is possible to avoid the consequences on the functional performance of the asset.
Condition-based tasks are inspections used to determine whether a potential failure is occurring since many failures show symptoms before reaching a point in which the functional failure occurs; it is recognized that sometimes the failure is occurring, but it has not progressed to the point of degrading the system’s functionality.
Since most failures are random in nature, RCM first questions whether it is possible to detect them in time to prevent the loss of the function of the system. There is a big difference between realizing that a failure is beginning to occur and it is about to not fulfill its role. Therefore, elapsed time between when a fault is potential and can be detected, and when it really occurs with a loss of function must be sufficiently long to be useful in defining a condition- based task and its subsequent right action.
The frequency of condition-based tasks has nothing to do with the regularity in which a failure occurs, but rather how quickly it happens. Therefore, it has nothing to do with the frequency in which the system or equipment has failed in the past.
MYTH 10:RCM and TPM are incompatible.
Some people fall into error generating conflicts between various initiatives simply because they believe the use of multiple methods is not compatible with schemes that can be called totalitarian and border on fanaticism.
Total productive maintenance (TPM) and RCM are complementary processes and they have very well defined and clear guidelines. On pages 155 and 172 of the book “TPM in Process Industries,” written by Tokutaro Suzuki and originally published by the Japan Institute of Plant Maintenance (JIPM), the author is clear and explicit when explaining the maintenance planned pillar at the stage of improvement maintenance effectiveness. One Suzuki statement taken from the book reads:
“To improve maintenance effectiveness, start by reducing equipment failures, process problems, losses such as quality defects, high equipment wear, low production, safety risks and environmental problems....you may need exploring new approaches to assist you in this task, such as RCM.”
Suzuki also quoted the definition of RCM from John Moubray, author of “Reliability Centered Maintenance.”
“RCM is a process to determine what should be done to ensure that any physical asset continues fulfilling its required functions in its current operational context. It is a highly structured framework, initially developed in civil aviation, allowing users to determine the most appropriate maintenance strategy for different assets.”
“A fundamental method to reduce processes failures is to select the most appropriate maintenance system for each of the functional components or major items of equipment. To do these, use the RCM methodology based on failure records and physical principles.”
Suzuki recommends using both methodologies with an orientation towards complementarity, not competition. With this approach, the pillar of planned maintenance allows you to coordinate efforts to define the best maintenance strategy.
Throughout this article, we have discussed 10 myths about RCM methodology implementation that is widespread in organizations. This is intended to provide clarity about the true strengths and forms of RCM application. In Part 2, 12 more myths will be discussed, thus completing a more comprehensive and clear vision about this process.
READ PART 2: MYTHS 11 - 22
