Mine ROI with Thermal Imaging
EP Editorial Staff | September 18, 2018
Infrared technology can be a powerful tool in your site’s quest for equipment reliability and operational cost savings.
This article is an expanded version of a feature that appeared in the September 2018 print and digital issues of Efficient Plant magazine.
Since heat is often an early symptom of equipment damage or malfunction, monitoring asset temperature levels should be a primary part of any preventive-maintenance (PM) program. Infrared technology simplifies the task of quickly spotting unusual readings that require further evaluation.
Monitoring equipment performance and scheduling maintenance when needed, in turn, can reduce unplanned downtime and associated costs and extend the lifespan of plant assets. Capturing these benefits, however, should not chip away at already precious maintenance resources. The goal is to transition those resources away from emergency repairs and into scheduled inspections of key equipment.
In many plants, infrared (IR) cameras are often the first tools technicians turn to for PM inspections. That’s because they can compare heat signatures
for all equipment on an inspection route, without interrupting operations. If a critical temperature is noticeably different from previous readings, personnel can leverage other technologies, i.e., vibration analysis, motor-circuit analysis, ultrasound, and lubrication analysis, to investigate the source of the problem and determine a course of action. For best results, it’s important to integrate data from all of those technologies into the same CMMS (computerized maintenance management software) system. Once IR data is correlated with that compiled from other technologies, the actual operating condition of all assets can be reported in an integrated format.
Thermal imaging can be used in a wide range of plant applications, including:
• monitoring and measuring bearing temperatures in large motors and/or other rotating equipment
• identifying “hot spots” in electronic equipment
• pinpointing leaks in sealed vessels
• finding faulty insulation in process pipes or other insulated processes
• spotting faulty terminations in high-power electrical circuits
• locating overloaded circuit breakers in power panels
• recognizing fuses at or near their current-rated capacity
• discovering problems in electrical switch gear
• capturing process temperature readings.
See the “Example IR Inspections” sidebar below for more examples.
Regardless of the type of equipment or system under evaluation, an effective IR inspection requires personnel to follow these basic steps:
- Reference existing lists of equipment from a CMMS or other maintenance-management software tool.
- Eliminate items that aren’t well suited for infrared measurement.
- Review maintenance and production records. Prioritize key equipment that’s prone to failure or often causes production bottlenecks.
- Employ a database or spreadsheet to group the critical equipment together, either by area or function, into roughly 2- to 3-hr. inspection blocks.
- Use the IR camera to capture baseline images of each piece of critical equipment. (Note: On some pieces of equipment, the technician may want to regularly capture multiple thermal images of key components or subsystems.)
- Download the baseline images into software and document the route with location descriptions, inspection notes, emissivity, and alarm levels, if appropriate.
- When the next inspection is due, if the technician’s IR camera supports the uploading of images, he or she can simply load those from the previous inspection onto the device and follow the onscreen prompts.
To capture the best thermal images, follow these best practices:
• Verify that the target system is operating at a minimum 40% of load (lighter loads don’t produce much heat, making it difficult to detect problems).
• Get close to the target and don’t “shoot” through doors, especially glass. When safety procedures allow, electrical enclosures must be opened or IR windows or viewports utilized.
• Account for wind and air currents. These powerful convective forces cool the abnormal hot spots, often below the threshold of detection.
• Account for ambient air temperatures, especially outdoors. In hot weather, the sun can heat up equipment while cold weather can mask the effects of overheating components.
• Keep in mind that not all problems are hot. Blown fuses and restricted flow in cooling systems are just two examples of situations where a problem is indicated by a cooler than normal signature. In other cases, a cold component is abnormal because of the current being shunted away from the high-resistance connection. (Note: Those who conduct IR inspections must understand how a machine works and be able to identify its heat-related failure signatures.)
• Consider sources for reflective infrared radiation. Items that have shiny reflective surfaces and are emissive will reflect infrared energy from other nearby objects, including the sun. This can interfere with target temperature measurement and image capture.
• Unpainted metals are difficult to measure. To improve measurement accuracy and repeatability, consider affixing “targets,” typically in the form of paper stickers, electrical tape, or painted spots, to such components.
• Accumulate numeric temperatures and thermal images, to facilitate long-term data analysis. Temperature trends will indicate where to investigate more, as well as where inspections can be less frequent.
• Once a database of baseline images has been compiled, associate an alarm temperature with each of them. Upload the most recent version onto the IR camera before each inspection. An alarm that goes off when a new measurement is taken indicates a significant change in temperature, which requires investigation.
CALCULATE YOUR SAVINGS
Studies by the U.S. Department of Energy’s (Washington, energy.gov) Federal Energy Management Program (FEMP), estimate that a properly working industrial PM program can result in cost savings of anywhere from 30% to 40%. Other independent surveys show that sustaining these types of programs results, on average, in the following:
• return on investment: 10 times
• reduction in maintenance costs: 25% to 30%
• breakdown elimination: 70% to 75%
• reduction in downtime: 35% to 45%
• increase in production: 20% to 25%.
To calculate the savings at your facility, estimate the costs of unplanned equipment failures. Then factor in human resources, costs for parts, and lost revenue from specific production lines. It’s important to keep a record of machine asset availability, production output, and the distribution of maintenance dollars and total maintenance costs over time. Those numbers will help calculate the return on your thermal-imaging and maintenance investment. EP
Example IR Inspections
The list of thermal-imaging applications in a plant or facility is long. Here are two common ones.
Checking motor bearings with a thermal imager is a good example of a preventive-maintenance (PM) task.
Start with a newly commissioned and freshly lubricated motor and take a “snap shot” with an infrared (IR) camera of the motor-bearing housing while the motor is running. Use this image as a baseline.
As the motor and its lubrication ages, the bearings become worn. As a result, heat-producing friction develops in the motor bearing, causing the outside of the bearing housing to heat. Take additional thermal images at regular intervals, comparing them to the baseline to analyze the motor’s condition.
When the thermal images indicate an overheating bearing, generate a maintenance work order to replace or lubricate the bearing housing and, in the process, reduce or eliminate the possibility of costly engine failure.
Finding leaks in sealed vessels is a “snap” with thermal imagers. Most leaks develop in or around a gasket or seal. Less often, corrosion causes a weakness to develop and rupture the vessel. Either way, an IR camera can diagnose the problem.
To find a leaky gasket or seal, scan the imager along the seal looking for thermal eccentricities. A large change in temperature along the seal or gasket indicates a loss of either heat or cold—the “signature” of a failure.
Information in this article was provided by thermal-imaging experts at Fluke Inc., Everett, WA. For more details on infrared inspections and related topics, visit fluke.com.