More than Sensors

Interest in Condition-Based Maintenance (CBM) has grown considerably in recent years. The demand for higher return on assets, the need to drive plants beyond normal production levels, the desire to lengthen plant lifecycles and the availability of new CBM technology have all contributed to this growth.

Many manufacturers are actively investigating how they can apply CBM to improve asset and asset management performance. Much of their attention is focused on new sensors for online corrosion measurement, vibration monitoring, model-based “smart sensors” and process asset management solutions that can infer asset condition from more general process measurements. While technology can help to drive improvement, it is not sufficient.

The output of an asset analysis is the equipment strategy to be followed in managing the equipment. An equipment strategy can include a variety of actions, from specific operating instructions to proactive tasks that are expected to reduce the likelihood or frequency of functional failure. Proactive tasks include two categories: preventive maintenance (PM) that dictates scheduled replacement or restoration of parts on a time or usage basis; and, predictive maintenance (PdM), which triggers actions according to actual equipment condition. PdM strategies reduce the cost of unnecessary maintenance and avoid the aggravating effect that PM can have for certain failures. Because PdM relies upon an asset’s condition, this approach is often referred to as Condition-Based Maintenance.

CBM is an appealing, effective alternative for many situations. The ability to minimize waste in the use of maintenance technicians and replacement parts is real, and can be quite significant for large enterprises. Organizations that adopt CBM can also adopt a more proactive approach to asset care that reduces unexpected, costly disruptions to operations by detecting pending failures and optimizing use of scheduled production downtimes.

Data that empowers

The value of CBM increases for assets with components that noticeably degrade over time. In these cases, condition monitoring can be used to track the asset’s status and this information can be used to predict degradation and failure. Operating personnel empowered with such information can modify their operating practices to accommodate the situation, or adjust their schedules to accommodate the needed repairs. Maintenance personnel can likewise use such information in work planning and parts management.

Sensor-based CBM naturally provides well-defined, quantitative values that can be tested against high/low limits and trends to identify abnormal states. Inspection-based measurements require definition of exactly what is to be measured, how the measurement is to be conducted and how the observations are to be classified. How do you understand “excessive play” in a connection without knowing what parts are involved, how “play” was assessed and what “excessive” means to the specific inspector? Establishing rules to guide inspection activities and to code results in a manner that supports analysis is a critical part of any successful CBM program.

CBM can be a powerful approach to better asset maintenance. But sensors alone do not provide an effective CBM program. Evaluate the value of CBM for your organization by considering the benefits of fewer unscheduled process interruptions and longer asset lifecycles. Incorporate the full scope of activities involved in CBM and what is required to make them effective as you develop your own program. Recognize the additional load that will be placed upon your internal maintenance experts as your CBM program develops, and explore how your equipment suppliers can help you manage this activity. Allocate funds for asset management interoperability in your CBM budget.

These investments will not only improve maintenance, they will also help the organization develop better operating practices and identify the best suppliers of operating equipment.

Sid Snitkin, ssnitkin@arcweb.com, is a vice president at ARC Advisory Group Inc., in Dedham, Mass.

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