This approach focuses on ensuring inherent reliability.
by Gregory Perry
December 3, 2018

In maintenance and reliability, buzzwords and “new” methods arise frequently. Many companies look for a quick fix to what must be a team-wide culture shift. Information about what data really matters and how to execute maintenance and reliability strategies has often been missing. Many teams feel pressure to implement condition-based techniques when they may just be getting scheduled maintenance off the ground, or they do not begin because they cannot use condition monitoring on all assets. How can teams in various states of reactive, preventive and predictive strategies move forward on their reliability journey? One way is to focus on asset capacity assurance.

Glossary of Terms

Capacity: The maximum amount that something can contain or obtain
Assurance: Confidence or certainty in the equipment’s ability to perform as designed
Maintenance: The process of upkeep or preservation or the state of being maintained

Defining CAPM

Capacity assurance maintenance (CAPM) addresses where corrective maintenance activities exist within the potential failure (PF) curve (see Image 1) to ensure the inherent reliability of an asset or system. Capacity assurance (CAPA) considers the entire continuum of maintenance reliability, from design for reliability (DFR), implementation or commissioning, precision maintenance best practices all the way to the corrective maintenance realm. CAPM is only focused on addressing equipment maintainability and the modes for which maintenance addresses an asset’s inherent reliability. This will ensure that assets are operational when called upon.

PF curveImage 1. The PF curve shows the failure curve and where on that curve condition monitoring technologies may detect the beginning of failure. (Images courtesy of Fluke Accelix)

Inherent Reliability

Inherent reliability (initial capability) is a measure of the overall “robustness” of a system or piece of equipment. It provides an upper limit to the reliability and availability that can be achieved.

No matter how much inspection or maintenance is performed, the inherent reliability can never be exceeded. If end users operate, maintain and monitor a device as well as possible, they will be able to harvest all the inherent reliability of the asset. If operations and maintenance or monitoring practices have gaps, end users will harvest only some of the inherent reliability.1

Inherent Availability

In reliability theory and reliability engineering, the term availability has the following meaning: The degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown or random time.2

In other words—uptime.

Availability is an important metric for assessing the performance of repairable systems, accounting for the reliability and maintainability of a component or system. Inherent availability is the steady state availability when considering only the downtime of an asset or system for corrective maintenance.

CAPM Work Categorization

Corrective task modes are described below and shown in Image 2.

Corrective task modesImage 2. Corrective task modes

Fault-Finding
Within the fault-finding mode two work identifying techniques are available: inspection-based and incidental-based. Inspection-based techniques—such as clean, inspect and lubricate (CILs), rounds; surveys; and audits—are used to detect potential problems (failures) and are considered scheduled (planned) work. Conversely, incidental-based identified work (such as work requests and ad-hoc work orders) are usually identified and addressed as an emergency breakdown (unplanned) schedule breaks. Incidental-based identified work can also drive scheduled work (planned) if not deemed a schedule break.

Time-Directed
Interval-based techniques use preventive maintenance that is calendar-based and/or meter-based. These strategies involve planned corrective work, but the work may not be needed on each asset. Again, time may be wasted with healthy machines that do not need intervention.

Condition-Directed
Condition-based techniques include predictive maintenance and condition monitoring. Based on the health of the asset, corrective work is planned as needed, minimizing emergency repairs and downtime.

Data-Directed
These corrective tasks are analytic-based using empirical data capable of being verified. Corrective work is then planned and carried out using the data obtained, often prescribed to the team using techniques (also called feature sets) associated with artificial intelligence and machine learning.

Securing Inherent Reliability

Corrective work secures the inherent availability of any asset or system. This does not include proactive maintenance (also known as reliability based maintenance) that address processes not associated with maintenance-related activities. Examples of proactive maintenance are defect elimination, precision commissioning, precision installation, work processes and procedures, lubrication reliability, 5S and operating for reliability.

One Solution: Connected Reliability

Teams want to ensure that their assets are available when needed. How can they move forward on the capacity assurance journey? The industrial internet of things (IIoT) can help maintenance and reliability (M&R) teams drive value and support them on the journey of maintaining inherent availability and CAPM.

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