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PdM, RCM and Reliability Management Systems

PdM, or predictive maintenance (also sometime referred to as condition-based maintenance, or CBM), is the practice of using condition-based monitoring techniques to collect and analyze data for the purpose of understanding asset performance and performing maintenance accordingly. PdM leverages predictive technologies, such as vibration and oil analysis, to identify potential failure modes in advance of actual failures. The benefits to asset owners are significant and often summarized as:

• Early warning of potential problems
• Fewer catastrophic failures
• Effective maintenance scheduling
• Reduced spare parts inventory
• Improved energy efficiency
• Validation of new installations or repairs
• Improved safety
• Improved overall system uptime
• Significantly reduced overall maintenance costs

In contrast, preventive maintenance (PM) is a time-based approach whereby asset owners take action according to schedules instead of actual asset performance. Reactive maintenance is the practice of taking action following run-to-breakdown.

PdM is an integral part of all modern reliability and maintenance programs. Maintenance professionals leverage PdM disciplines to help improve asset reliability and ultimately, asset value.

Reliability-centered maintenance, or RCM, is an engineering framework used by asset owners to assess, plan, monitor and maintain mission critical assets. It follows the modern management approach of plan, do, check, act – also known as the PDCA cycle and made popular by Dr. Edward Deming. Other similar frameworks also are used; some examples include Business Centered Maintenance (BCM), Risk-centered Maintenance (RiCM), and Streamlined RCM, to name a few. In theory, each of these process frameworks have subtle but significant differences. In practice though, organizations each develop a reliability management system dictated by the particular needs and culture of the organization.

Historically, maintenance programs have combined time-based monitoring and reactive maintenance practices with little success improving the overall reliability process. RCM requires asset stakeholders to better understand their assets, often using condition-based monitoring techniques, so that maintenance practices are conducted with the specific objective of improving overall reliability and asset value.

Organizations with world-class reliability and maintenance processes became world-class by operating their processes within the context of a formal reliability management system.

The governing standard for RCM processes is SAE JA1011. This standard establishes the minimum requirements for RCM processes. Asset owners may use this standard to evaluate whether their reliability processes are in fact reliability-centered maintenance processes.

RCM requires asset owners to answer the following questions with respect to each critical asset:

1. What are the functions?
2. What are the functional failures?
3. What are the failure modes?
4. What are the failure effects?
5. What are the consequences of each failure?
6. What can be done to predict or prevent each failure?
7. What can be done if the failure is not predictable or preventable?

These questions are usually answered by preparing an asset inventory and completing a risk assessment using a standard methodology, such as failure mode, effects, and criticality analysis (FMECA). Formalized risk assessments are useful tools for ensuring the questions are answered using cross-functional teams, with relative objectivity and with a consistent approach for valuing risk.

Solutions to question six, and the actions plans resulting from the risk assessments, focus on using PdM technologies and condition-based monitoring. RCM encourages the use of PdM, specifically in regard to failure management policy selection and scheduled tasks.

Simply, RCM requires assets owners to develop an intimate understanding of their assets and how they operate. PdM and condition-based monitoring is the practice collecting data, analyzing data, sharing information and taking preventive action to increase overall asset value.

PdM → PM → Reactive Maintenance