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Predictive Maintenance

Temperature Gun or Thermographic Camera: How to Find your Way Around

September 20, 2022

Infrared thermography is a thermal measurement process that detects areas of heat on a surface that are invisible to the naked eye.  It is an effective tool for predictive maintenance as it can help identify potential problems before they lead to equipment failure. By monitoring temperature changes, we can detect various factors of malfunctioning mechanical elements such as over-greasing, misalignment, and other anomalies. This allows corrective action to be taken before the situation deteriorates, thus avoiding costly repairs and unplanned downtime.
Pyrometers, commonly called temperature guns, are often used in industrial applications. But what is the difference between thermographic cameras and pyrometers? Both work on the same principle: they use infrared technology to detect infrared radiation and translate it into a temperature reading. However, a thermal camera has many advantages over pyrometers. Primarily, the pyrometer only measures the temperature of a single point and is therefore limited in its ability to measure larger areas. In contrast, thermal imaging cameras use infrared technology to create an image of the surface being measured. This allows them to take readings from multiple points and quickly identify areas of high heat.
Using a pyrometer can therefore generate misleading or simply wrong readings. The laser pointer of the pyrometer is a guide to where the instrument is pointed but will not provide an overall measurement of the component. Therefore, the operator, in the absence of an indication that the equipment is defective, may not consider its actual temperature.
A similar situation occurred at a large pulp and paper mill. Laurentide Controls was commissioned to set up and run a mechanical and process thermography route to identify any anomalies.  This route was to be executed every two months. During one of these visits, Laurentide Controls' expert identified the temperature of a pillow block bearing as being over 125°C, an increase of 75°C from the last visits. When the paper mill team was informed, a technician was dispatched to the site to validate the temperature, identify the anomaly and correct it if possible, specifically, to lubricate the bearing to reduce the temperature.
However, the technician still reported a temperature of 50°C. At the request of the reliability engineer to recheck this result, the technician took new readings and obtained contradictory results: 60°C, 45°C and 90°C. How can the discrepancies between the results be explained and, above all, which reading should be trusted to make an informed decision?
Noting that the technician had used a pyrometer, Laurentide Controls' specialist was able to guide him to detect the heat point, thus confirming his initial temperature reading of 125°C. While the heat gun can be very useful for some tasks, it has limitations that make the overall readings less accurate. Since it only measures the temperature of one location, it can be easy to miss crucial information. However, this data could be critical in identifying potentially catastrophic equipment failures, which could even result in a fire.
After investigation, the Laurentide Controls specialist and the technician were able to identify deterioration inside the bearing; it was only a matter of time before the equipment failed, which could have resulted in an unscheduled shutdown of over five hours. Fortunately, the identification of the equipment damage occurred on a weekday when the maintenance crew was fully staffed at the mill, saving them valuable hours. The paper mill was also aided by its good spare parts management, as the part was available in inventory, saving them several extra hours of unplanned downtime.
The efficiency and accuracy of the thermographic camera helped identify an anomaly that could have been very costly for the plant. Regular diagnosis of industrial facilities is essential to maintain optimal operation and avoid unexpected downtime. Thermal imaging is an easy and effective tool that can be used to detect potential electrical or mechanical problems before they cause damage. It can be used to locate process anomalies: thermal insulation, thermal profile, steam trap operation, etc.  This is a good first step towards a predictive maintenance program. By regularly diagnosing industrial installations, operators can target and plan maintenance, anticipate or postpone interventions according to the plant's management priorities.

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