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What Is Reliability-Centered Maintenance?

September 21, 2020

What Is Reliability-Centered Maintenance (RCM)?

Reliability-Centered Maintenance (RCM) is a corporate-level maintenance strategy designed to optimize maintenance programs by establishing safe minimum levels of equipment upkeep. RCM emphasizes matching individual assets with the maintenance techniques most likely to deliver cost-effective outcomes. The successful implementation of RCM enhances reliability, equipment uptime, and company savings. 

Overview

Reliability-Centered Maintenance (RCM) is a complete framework that always attempts to extend equipment lifespans and decrease downtime, in the most cost-efficient way possible. The primary objective of RCM is best understood by analyzing its root words: 

Reliability: The quality of performing consistently well. 

Maintenance: Ensuring assets continue to function as desired. 

Essentially, Reliability-Centered Maintenance (RCM) provides a roadmap to analyze and act upon the root causes of equipment failures—technology, culture, design, and maintenance strategy inefficiencies—in pursuit of affordable asset reliability. 

Of course, downtime is inevitable when working with complex pieces of machinery. However, top-tier organizations use RCM to prevent sudden breakdowns that require laborious maintenance, costly outsourcing, and lost production time. 

What Makes RCM Different From Standard Maintenance Programs? 

RCM recognizes that all facility assets are not of equal importance—from both safety and process standpoints. The decision-making framework seeks to best match equipment needs with available resources for cost-effective reliability. 

Translation: Some assets are more integral to daily production goals than others, and assets don’t always fail for the same reasons. Thus, RCM provides a management roadmap for prioritizing, optimizing, and assigning maintenance activities.

reliability centered maintenance
Guidance on RCM development by equipment application (adapted from NASA 2000)

According to the O&M Best Practices Guide, Release 3.0, top-performing facilities on average divide their maintenance efforts into the following categories based on RCM: 

  • <10% Reactive Maintenance
  • 25% to 35% Preventive Maintenance 
  • 45% to 55% Predictive Maintenance 

Because RCM emphasizes newer predictive maintenance technologies—such as infrared, acoustic (partial discharge and airborne ultrasonic), corona detection, vibration analysis, sound-level measurements, and oil analysis—the process isn’t financially feasible for small-to-medium-sized companies. However, RCM has earned a “government seal of approval.” 

United Airlines executives developed the process before catching the attention of the U.S. Department of Defense in 1978. Today the maintenance process is practiced by hundreds of industrial and service organizations around the world.

The Principles of Reliability-Centered Maintenance

The RCM paradigm argues that the less maintenance you perform on an asset, the better. Only perform maintenance when absolutely necessary or when the benefits outweigh the risks and costs. RCM is based on four key objectives: 

  • Preserve system functions.
  • Identify failure modes that can affect system functions.
  • Prioritize identified failure modes according to risk and cost projections. 
  • Select the most effective tasks to control failure modes. 

The Requirements of Reliability-Centered Maintenance

Organizational leaders should outline their RCM goals by considering management availability, accessible technologies, and budgetary resources. This somewhat time-consuming process carefully analyzes individual asset scenarios before assigning corresponding maintenance tasks.

Below are the evaluation criteria for RCM, as described by the Society of Automotive Engineers (SAE). Assess each piece of equipment, organized by phase, by asking: 

Phase 1: Decision

  • What functions does it perform, and what are the desired performance standards?
  • In what ways could the asset fail to fulfill its functions? 
  • What are the causes of each possible failure scenario?

Phase 2: Analysis 

  • What happens when each type of failure occurs?
  • What consequences would we suffer as a result of each failure?
  • How could we predict or prevent each failure?

Phase 3: Action 

  • What should we do if we can’t determine a suitable proactive task?

The final component of RCM is choosing and scheduling appropriate maintenance tasks. A computerized maintenance management system (CMMS) can schedule, assign, and oversee work orders. As expected, different techniques are suitable for different asset situations. Some machinery may require proactive tasks, including preventive and predictive maintenance. Conversely, reactive maintenance may be the most financially prudent course of action for other low-importance pieces.


reliability centered maintenance
Guidance on RCM development by equipment application (adapted from NASA 2000)

Advantages and Disadvantages of Reliability-Centered Maintenance

Successfully implementing RCM benefits organizations that can afford it. The framework takes the guesswork out of maintenance prioritization and helps organizations maintain assets in a consistent, structured, and cost-effective manner. 

Because RCM heavily relies on predictive maintenance (PdM) technologies, its program advantages and disadvantages mirror those of it. However, RCM allows facilities to match resources to equipment needs more closely while improving reliability and decreasing cost—more than any one singular PdM strategy. 

Advantages

The advantages of reliability-centered maintenance include: 

  • Cost-effectiveness. RCM helps reduce costs by minimizing unnecessary routine maintenance tasks. When combined with preventive maintenance, RCM has been shown to reduce workloads by 70 percent.
  • Better Teamwork. RCM takes a group approach to maintenance tasks. Communication and cooperation among departments and teams improve when everyone is involved in problem analysis and decision making.
  • Improved Asset Performance. It also eliminates unnecessary overhauls and, therefore, reduces shutdowns. RCM also helps to diagnose failure more quickly.
  • Improved Employee Motivation. When employees are involved in the application of RCM, they get a better understanding of the assets in their operating contexts. This motivates them to take ownership of maintenance problems and solutions.
  • Better Safety and Environmental Integrity. RCM seeks to understand the implications of every failure mode and takes proactive steps to prevent them. Besides limiting failures, the maintenance prioritization process promotes the availability of necessary protective devices.

Here’s an example of RCM’s benefits: The NASA Marshall Flight Center saved more than $300,000 in costs by implementing an RCM strategy that reduced maintenance costs, improved workplace safety, and extended the lifespan of aging assets. The program also enabled the Center to minimize its energy consumption and reduce its environmental impact. 

Disadvantages

RCM also has its drawbacks. The initial costs of implementing RCM are high. Performing RCM analysis requires teams to invest significant time, finances, and resources to get started. ROI may be slower than executives prefer. 

The second major disadvantage of RCM is that it simultaneously incorporates all of the other types of maintenance strategies, including some of their drawbacks. 

For instance, say you choose a run-to-failure approach for a given asset. You simultaneously run the risk of an unplanned failure. For this reason, RCM is sometimes seen as expensive compared to running predictive or preventive maintenance programs alone. However, most experts agree that RCM is more cost-effective in the long run. 

How to Run a Reliability-Centered Maintenance Program

The best way to implement an RCM program–which can be daunting–is to take a logical approach and handle one step at a time. While there are different ways of implementing RCM, these six basic steps are a great place to start: 

Step 1: Select an asset RCM analysis.

Choose an asset on which to perform the RCM analysis. What criteria should you use to select the asset? Some factors to consider include how critical the asset is to operations, its repair costs in the past, and its previous preventive maintenance costs.

Step 2: Outline the functions of the system for the selected asset.

It’s important to know the functions of the system including its inputs and outputs, no matter how small. For example, the inputs of a conveyor belt are the goods and the mechanical energy that powers the belt.

Step 3: Define the failure modes.

Understand the different ways in which the system can fail. For example, the conveyor belt may not transport the goods fast enough or completely fail to transport them from one end to the other.

Step 4: Assess the consequences of failure. 

What will happen in the event of a failure? Asset failure can result in safety concerns and poor business performance. It also can affect other equipment. Plant operators, equipment experts, and technicians should work together to identify the root causes of individual asset failure. This process helps determine how to prioritize tasks.

 You can organize this process using many methods, including: 

  • Failure Modes and Effects Analysis (FMEA): This is a method of evaluating the impact of a failure by identifying where and how a process might fail. For example, what would make the conveyor belt slow down or stop working? 
  • Failure, Mode, Effect, and Criticality Analysis (FMECA): This is the same as FMEA. However, it goes one step further and creates linkages between failure modes, the effects, and the causes of failure.
  • Hazard and Operability Studies (HAZOPS): HAZOPS is a systematic examination of processes to identify issues that may result in risks for your personnel and assets. In most cases, it guides the review of standard operating procedures.
  • Fault Tree Analysis (FTA): The FTA is a graphic tool used to examine the cause of system-level failure. It employs a top-down deductive analysis of failure.
  • Risk-based Inspection (RBI): RBI is a decision-making process used to optimize inspection plans. It’s primarily used to examine industrial equipment, such as piping, pressure vessels, and heat exchangers.

Always prioritize the more critical failure modes for additional analysis. Retain the failure modes that can occur in a real-life operating environment.

Step 5: Determine a maintenance strategy for each failure mode.

At this point, select a maintenance strategy for each critical failure mode. It should be both economically and technically feasible. You can use condition-based maintenance (CBM), preventive maintenance, or predictive maintenance (PdM). If you are unable to implement a given strategy for a particular failure mode, consider redesigning the system to modify or eliminate the failure mode.

Non-critical failure modes can be considered for a run-to-failure maintenance strategy. At this stage, you are looking to answer the question, “What is the principle of an effective maintenance strategy?”

Step 6: Implement the strategy and perform regular reviews.

For your RCM program to be effective, you need to implement the maintenance recommendations identified in Step 5. After implementation, regular reviews will help to improve the systems and performance. Whichever maintenance strategy you decide to use for each asset, you will be able to generate additional data that will improve your systems.

History of RCM

Understanding the history of RCM may help you better appreciate the program and better understand how to establish it within your company. As with many advanced forms of maintenance, the origins of reliability-centered maintenance began in the aviation industry. During the 1960s, the aviation industry was on the verge of building the world’s first jumbo-jet aircraft. The Boeing 747 was taking shape in Seattle, but there was a problem: preventive maintenance would not be economically feasible to keep the 747 in shape. The industry needed to rethink its maintenance strategy.

United Airlines led a reevaluation of the preventive maintenance strategy. It spearheaded a review of the importance of maintenance and the best way to accomplish maintenance goals. The result of these efforts was the reliability-centered maintenance strategy. United Airlines first applied the new strategy to the Department of Defense (DoD) aircraft in 1972. It was the DoD that christened the strategy as reliability-centered maintenance and directed its application on all major military systems. The Airforce Institute of Technology now offers a course on RCM and the Navy has published a handbook for RCM.

In 1983, the Electrical Power Research Institute (EPRI) initiated pilot studies on how RCM could be used in nuclear power plants. These led to the full-scale application of RCM in commercial fossil and nuclear power plants. Since then, RCM has evolved into being used in commercial aviation as well as in the manufacturing, healthcare, mining, and transport industries, among others.

RCM has not only helped to identify potential risks and mitigate them but also aligns maintenance tasks to business goals and helps achieve compliance with regulatory, safety, and environmental requirements. While no industry has yet fully embraced RCM, its use has become more wide-spread.

Today, the Federal Aviation Administration (FAA) requires all aircraft owners and operators to have an FAA-approved preventive maintenance program. It’s one of the many requirements of Type Certification before an aircraft is licensed by the FAA. 

RCM Resources 

  • An Introduction to Reliability and Maintainability Engineering; By: Charles E. Ebeling; Published by: McGraw Hill College Division Publication date: September 1996. 
  • Maintenance Engineering Handbook; By: Lindley R. Higgins, Dale P. Brautigam, and R. Keith Mobley (Editor), Published by: McGraw Hill Text, 5th Edition; Publication date: September 1994.
  • Condition-Based Maintenance and Machine Diagnostics; By: John H. Williams, Alan Davies, and Paul R. Drake Published by: Chapman & Hall; Publication date: October 1994. 
  • Maintenance Planning and Scheduling Handbook; By: Richard D. (Doc) Palmer Published by: McGraw Hill Publication date: March 29, 1999. 

Conclusion

Reliability-centered maintenance programs allow organizations to choose the most cost-effective AND reliable maintenance strategy for each asset. RCM programs reduce unnecessary costs, improve safety, and eliminate unnecessary work orders. Larger organizations that can afford to implement advanced periodic maintenance strategies benefit most from RCM’s holistic framework.

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