Maintenance and reliability are professional fields with certifications available to highly trained personnel. There are numerous outlets for training; typically through specialized engineering consultants. There is also a well-defined body of knowledge, including applicable textbooks and professional organizations.
The most popular certification is the CMRP, or Certified Maintenance and Reliability Professional and CMRT Certified Maintenance and Reliability Technician. The Society of Maintenance and Reliability Professionals offers this certification and various training programs. Training is also available from reputable consulting firms, such as the Marshall Institute in Raleigh, N.C. and Life Cycle Engineering in Charleston, S.C.
There is large professional network that can help you with understanding maintenance, including several groups on LinkedIn.
A few highly recommended authors and textbooks include:
“Maintenance Best Practices 2nd Edition” — Ramesh Gulati
“Reliability-Centered Maintenance Second Edition” — John Moubray
“Rules of Thumb for Maintenance and Reliability Engineers” — Ricky Smith, Keith Mobley
These texts are a great source of applicable knowledge and are referenced throughout this blog series. Each also present foundational points that aid in basic training and communication, including:
1. Types and methods of maintenance
2. Maintenance versus reliability
3. Commonly observed metrics
4. Benchmarks of performance
What is Maintenance?
main·te·nance – noun
the process of maintaining or preserving, or the state of being maintained
When it comes to industry, maintenance is the activity to preserve the functions and capacity of required equipment and processes. Maintenance is a requirement for sustainable success. Well-structured maintenance programs have a direct correlation to quality as well as equipment performance and availability.
What Defines a Successful Maintenance Organization?
The ultimate goal of maintenance is to provide optimal reliability that meets the business needs of the company, where reliability is defined as “the probability or duration of failure-free performance under stated conditions.”
Smith, Ricky; Mobley, R. Keith; (2011-03-31). “Rules of Thumb for Maintenance and Reliability Engineers.” Elsevier Science.
This very act of preservation requires investment today for future benefits, and that is where things get difficult for maintenance. In earlier times, maintenance teams were highly praised for responding to breakdowns. The impact of maintenance was clearly visible. The role of maintenance has since evolved to prevent breakdowns from occurring rather than react to them. Thus, there are no celebrations for the recovery from disaster because they prevented the disaster. The success introduces new pressures from finance and other areas, which begin to challenge the investment made in “preservation.”
The hard reality is that the better maintenance performs, the more it has to fend off those who want to cut it. Fortunately, there are commonly shared metrics that can be used to make comparisons or showcase the impact of a great program.
Types of Maintenance
There are two major categories of maintenance activity – keeping things from breaking and fixing broken things. Preventive maintenance includes time-based, conditioned-based and predictive activity. Preventive maintenance often results in findings that lead to the second major category – corrective. This includes routine, major and emergency repairs. The following definitions can be found in “Maintenance and Reliability Best Practices” by Ramesh Gulati.
Condition Based Maintenance (CBM)
Also known as Predictive Maintenance (PdM). Maintenance based on the actual condition (health) of assets obtained from in-place, non-invasive measurements, and tests. The ultimate goal of CBM is to identify proactive maintenance actions to be performed at a scheduled point in time when the maintenance activity is most cost effective and before the asset fails in service.
Preventive Maintenance (PM)
A maintenance strategy based on inspection, component replacement, and overhauling at a fixed interval, regardless of its condition at the time. Usually, scheduled inspections are performed to assess the condition of an asset. Replacing service items (filters, oils, and belts) and lubricating parts are a few examples of PM tasks. PM inspection may require another work order to repair other discrepancies found during the PM.
Capital Project Maintenance (CPM)
Major repairs, e.g., overhauls and turnaround projects, valued over a certain threshold are sometimes treated as capital projects for tax purposes. If these projects are essential to restoring the asset back to the designed capacity — not to add additional capabilities — they should be treated as maintenance costs.
Corrective Maintenance (CM)
Repair actions initiated as a result of observed or measured conditions of an asset after or before the functional failure. CM may be planned (scheduled) or unplanned (reactive).
There are multiple relationships between these programs, and established KPIs to help evaluate their effectiveness. A few rules of thumb(1) for best in class programs are:
1. Planned maintenance should be greater than 85 percent of maintenance.
2. Unscheduled (reactive) maintenance should be less than 10 percent.
3. PMs should be conducted within +/- 10 percent of schedule to be in compliance.
4. Each hour of PM or CBM should yield .5 to 2 hours of corrective maintenance (PM effectiveness, PM yield).
Unplanned motor failure is extremely detrimental to these KPIs. Most motor reliability programs, therefore, include a combination of CBM strategies and
defined repair practices. The goal is to support the objectives of maintenance and operations at the lowest cost per horsepower possible. Improvements in technology have created new methods of maintenance optimization that help find the balance between cost and reliability.
Our next post will introduce reliability centered maintenance, or RCM, and contrast it with condition based maintenance.
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(1) Gulati, Ramesh (2012-08-17). Maintenance Best Practices. Industrial Press, Inc.