Infrared Thermography / Temperature Monitoring

Thermal evaluations enhance predictive maintenance

A predictive maintenance strategy uses thermal imaging to achieve positive, verifiable, cost-justifiable results.

By Fernando Lisboa

What do discrete manufacturing, continuous processing and power generation have in common? Integrated and increasingly interdependent production equipment renders each vulnerable to failure if equipment stops or fails and crashes completely. When critical operating systems malfunction unexpectedly, costs increase, manpower and material get shuffled and productivity sags.

Competition requires maximizing efficiencies that increase productivity, a task achieved most effectively with a comprehensive predictive maintenance (PdM) program. A PdM strategy uses thermal imaging and other predictive maintenance tools to fulfill specific objectives and achieve positive, verifiable, cost-justifiable results. Using infrared imaging (thermography) and other inspection technologies, PdM can mitigate the effect of, or prevent entirely, failure-prone electromechanical systems from going offline.

According to R. Keith Mobley, the author of An Introduction to Predictive Maintenance, eliminating unscheduled and unnecessary repairs reduces the need for corrective maintenance by as much as 90 percent over five years. Mobley asserts that a successful PdM program reduces the lifecycle cost and extends the useful life of critical systems by as much as 60 percent and increases labor utilization by as much as 85 percent. When fully implemented, a PdM program can generate a return on investment well above 100:1.

A successful predictive maintenance program requires monitoring critical production systems to determine the baseline operational profile against which suspected operating anomalies can be identified, measured and corrected. While the cost of a PdM program is higher than a conventional maintenance program, consider the even greater cost of just one avoidable, catastrophic failure.

Thermal imagers

Heat often is an early indication of damage or malfunction. That's why it's a major performance variable an effective PdM program routinely monitors. Portable, hand-held, non-contact thermal imagers scan and record the temperature and infrared thermal image of crucial equipment.

Data and images in the equipment profile are downloaded to a PC for analysis and comparison with earlier thermal imaging scans. The resulting performance evaluation of key production, processing and power generating components enhances the ability of the PdM program to predict the need for maintenance.

Infrared imagers can detect dysfunctional pumps and underperforming surface heat exchangers and identify problems in a variety of plant systems and equipment, including switchgear, electrical substations, circuit breaker panels, motors, gearboxes, transmissions, building envelopes, bearings, steam lines and process systems that rely on heat retention or transfer. Unlike vibration analysis, oil analysis and wear particle analysis, thermography is well-suited to monitoring most production and processing equipment. Multi-functional, low-cost thermal imagers are now priced quite economically.

Know your tools

The effectiveness of the thermal facet of a predictive maintenance program depends on becoming knowledgeable about the performance capabilities of thermal imaging tools. For example, one must recognize the tradeoff between imager functionality and ease of use. A thermal imager having only nominal functions and requiring minimum instruction for use may well serve the requirements of a large production facility in which an ultra-sophisticated, difficult-to-use imager would constitute overkill.

Of equal importance is training. A good training program should be included in the imager's price. Certified thermographic trainers should conduct the classes at locations close to the user's plant. Talk with users who have gone through the program. Not only should they feel trained and ready to operate an imager effectively, but also to do so within the rigorous guidelines of a strategically designed and proactively implemented predictive maintenance initiative. With adequate, yet minimal training, non-supervisory maintenance personnel should be able to become cost-effective thermographers, fully capable of implementing or expanding a results-oriented PdM program.

Consider imager operational factors, such as operator safety. For example, is it necessary for the operator to sight a target through an eyepiece to use the imager? If so, ensuring operator safety during inspections may necessitate a safety assistant guiding the imaging operator. Shouldn't that safety guide be assigned to more important duties?

The weight and size of an infrared imager may affect data collection, too. Heavy, bulky, cumbersome units may require physically strong personnel, possibly excluding some members of the maintenance staff. If the imager is oddly shaped or awkward, the operator may not be able to get close enough a target to scan hard-to-access equipment. Don't assume that all imagers are ergonomically equal. They aren't.

Temperature range

Of great significance is an infrared imager's ability to measure a range of temperatures. Some equipment normally runs hotter than other equipment. An imager with an inappropriately low upper temperature limit may not be suitable for a facility's most important production or processing equipment. Look for imagers with an upper ambient temperature of at least 500 F, and a lower ambient temperature of 32 F or less.

Batteries

Battery life may be crucial to the ability of an imager to get from point A to point Z. Imagers with batteries allowing for only three or four hours of operation won't function through an entire eight-hour shift. Find an imager that will, especially if the batteries require overnight recharging.

Analysis

Don't pay extra for thermal imager software. The best deal is to have the software bundled with the imager and included in the unit's price. Only imagers that support data and image downloading for storage and interpretation to any PC are acceptable for a serious PdM program.

Maintenance professionals considering the purchase of an infrared imager should expect answers to plant-specific operating questions and help evaluating thermal imager and predictive maintenance needs. End users shouldn't struggle to connect the dots; vendors can help identify and achieve manageable objectives and help set realistic expectations about what constitutes reasonable payback and successful thermal imager operation. Information about these and related issues also can be found in the imager's user manual, which should be available for downloading from the Web.

For instance, many production lines have hourly downtime costs exceeding $10,000. At that rate, the payback on a high-performance imager can be as little as one hour. Working with detailed payback information from the imager manufacturer, users can calculate a realistic rate of return that accrues from initiating or expanding thermal imaging capabilities.

In the plant

Once a purchase is made, expect help developing a strategy for the optimal use of a thermal imager within an existing or to-be-established PdM program. For some, the commitment to a comprehensive predictive maintenance program will be incremental. For those not yet ready to commit to a full PdM effort, the availability of low-cost, high-performance thermal imagers can facilitate immediate production equipment monitoring, data acquisition and maintenance efficiencies. As a good first step, thermal imaging provides results in the shortest time at the lowest cost while positioning users for the future establishment or expansion of a predictive maintenance program.

Fernando Lisboa is Thermal Imaging Product Manager, Portable Products Division, for Raytek, Inc., Santa Cruz, Calif. He can be reached at fernandol@raytek.com.