Reliability, from an engineering perspective, is commonly defined as the
likelihood of a system performing its intended function under planned and
unplanned circumstances.
Generally speaking, maintenance and reliability professionals are concerned with the reliability
of two types of systems:
- Electro-mechanical systems;
- Production systems.
Typical electromechanical systems include pumps, fans, compressors, mills,
gearboxes, motor control centers, substations; in essence, all of the assets
necessary for the production system to function effectively. The production
system is the collection of processes, which include the electromechanical
systems, that transforms resources into useful goods and services.
The ITR reliability team views reliability as a process. As with any process, the
objective is to establish a measurable target and ensure the process is as
accurate and precise as possible. Accuracy is a measure of how well the average
or mean of data relate to a target value. Precision is the net effect of
discrimination, sensitivity and repeatability over an operating range and is a
measure of the data width variation.
By nature, all processes exhibit some variation. When reliability is viewed as a
process, reliability and maintenance professionals understand there are two
types of variation: controlled and uncontrolled. Controlled variation is usually
associated with common causes and is consistent over time. Uncontrolled
variation is usually associated with special causes and changes over time. As
can be seen in the process diagram below, there are many factors influencing
variation.
ITR’s reliability team strives to help customers
reduce controlled variation and eliminate all uncontrolled variation through the
use of predictive technologies. Controlled variation in the reliability process
can be caused by routine equipment wear and the influence of planned preventive
maintenance, among many other factors. Examples of causes of uncontrolled
variation include unplanned outages due to catastrophic equipment failures and
spare part stock outs.
By understanding reliability as a process, ITR is able to work with its partners
to ensure their predictive maintenance efforts are best suited to their exiting systems and relate the effectiveness of the reliability process to
measurables understood by top management.
PdM, RCM and Reliability Management Systems