There's major benefitts to building condition assessments into regular predictive maintenance

Building them into the regular predictive maintenance program offers certain benefits

By R. Keith Mobley, Contributing Editor

 

An essential part of effective facility, plant or maintenance management is periodic assessments of the reliability, maintainability, remaining useful life, feasibility of continued operation and total operating cost of the facility's assets. While more progressive companies are embracing this condition assessment, too many attempt to conduct the assessments using subjective judgements instead of hard numbers. For example, roof assessment might involve either a simple visual inspection or a phone call to the building manager to ask about the current condition of the roof. Obviously, these methods provide little real value and can often lead to bad business decisions later.

Condition assessments take many forms, but each requires fundamental elements, including:

A clear understanding of the individual asset's criticality.

A hierarchy showing how each asset fits into the overall facility infrastructure.

A complete Simplified Failure Modes and Effects (SFMEA) analysis.

Effective techniques to quantify the variables that define "condition."

The SFMEA identifies each asset's potential failure modes and specifies the inspection methods that should be used to quantify its condition. The analysis can't be done without an understanding of the hierarchy and the asset's contribution to the facility's ability to meet its mission.

The normal progression of any continuous improvement project starts with an initial condition assessment during the first year of use to establish a reference or baseline data set for an asset. The data are used to detect performance changes and to project future needs. The assessment provides a quantifiable definition of the inherent reliability of a critical asset, as well as a comprehensive list of deficiencies that must be resolved to ensure continued reliability, maximum useful life and lowest life cycle cost.

While the knowledge gained from such a facility assessment is an invaluable tool, the associated costs are high. The only controllable variable is the method used to conduct the baseline and subsequent assessments. Because of the potential for distorted or erroneous results and the high cost of labor and test equipment required to perform a total facility assessment, extreme care must be taken to ensure that the assessment generates accurate, cost-effective metrics. Methods used must include a way to obtain quantifiable data to eliminate perceptions and opinions. For example, roof surveys should use infrared imaging that accurately detects leaks and degradation in the roof surface.

Most facilities perform baseline and follow-up assessments as part of a predictive maintenance program. Rather than incur duplicate costs by performing a separate assessment, a plant can blend the efforts into the traditional predictive baseline. By definition, a predictive maintenance program periodically evaluates the operating condition of critical assets and doing so, in most cases, eliminates the need for a separate periodic condition assessment.

Another option is to extend a condition assessment project over a longer time period. A traditional total facility assessment uses hierarchy and criticality analysis to guide the evaluation sequence. Initially, evaluation starts with critical infrastructure and progresses to non-critical and non-infrastructure assets in order of decreasing criticality. The process continues until every asset has been evaluated. Manpower availability, facility size and systems and facility complexity determine the assessment timeframe. In small facilities, the entire process may require only a few weeks, but in larger, more complex plants, the effort may require six to nine months.

A quantifiable condition assessment is an extremely valuable management tool that provides the knowledge needed to manage the life cycle costs of critical assets effectively. If combined with an effective condition monitoring or predictive maintenance program, managers will have the factual data needed to achieve and sustain optimum reliability, useful asset life and best life cycle cost.

Contributing Editor Keith Mobley can be reached via email at rkmobley@aol.com.

 

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