Plant & Works Engineering
Thermal imaging: cost-effective contribution to preventive maintenance
Published:  23 November, 2020

Monitoring equipment performance and scheduling maintenance when needed reduces the likelihood of unplanned downtime due to equipment failure. This saves the costs of “reactive maintenance” fees and equipment repair costs, while extending the lifespan of machine assets. Andy Pye reports.

Heat is often an early symptom of equipment damage or malfunction, making it important to monitor in preventive maintenance programs.

Using thermal imaging regularly to check the temperature of critical equipment makes it possible to track operating conditions over time and quickly identify unusual readings for further inspections. Thermography (otherwise known as thermal imaging) uses infrared-sensitive cameras to inspect buildings, electrical equipment and rotating machinery to find faults associated with heat loss or gain. Infrared cameras have developed significantly over recent years: some modern thermal imaging cameras are now so small they can fit in the palm of a hand.

Therefore, thermal cameras are often the first inspection tool a technician thinks to use as part of their preventive maintenance program. They can swiftly measure and compare heat signatures for all equipment on the inspection route, all without interrupting operations. Applications include HVAC maintenance to electrical inspection and building envelope surveys. Electrical and mechanical systems tend to get hot before they fail; air duct leaks and excess moisture are often colder than their surroundings. By detecting these temperature anomalies, thermal imaging allows facilities maintenance crews to take corrective action and avoid costly maintenance and repair.

Another advantage of thermal imaging is it can pinpoint energy losses in a building without any destructive testing methods. Pairing the thermal imaging camera with methods such as ‘Blower Door’ systems can speed up inspections immensely. The camera is a reliable non-contact instrument that can scan and visualize the temperature distribution of entire surfaces quickly and accurately. Thermography programs have contributed to substantial cost savings around the world.

If the temperature is noticeably different from previous readings, facilities can then use other maintenance technologies - vibration, motor circuit analysis, airborne ultrasound, and lube analysis - to investigate the source of the problem and determine the next course of action.

For best results, all maintenance technologies should be integrated into the same computer system, so that they share the same equipment lists, histories, reports and work orders. Once the infrared data is correlated with data from other technologies, the actual operating condition of all assets can be reported in an integrated format.

To calculate the savings at a facility, estimate the costs of unplanned equipment failures. Then factor in human resources, costs for parts, and lost revenue from specific production lines. It would be wise for the maintenance manager to keep a record of machine asset availability, production output, and the total maintenance costs over time. Those numbers will help calculate the return on a thermal imaging and maintenance investment.

According to Fluke, studies by the US Federal Energy Management Program (FEMP), estimate that a properly working preventive maintenance program can lead to savings of 30 to 40%.

Cameras to look at

Costing around £10k, the Fluke Ti480 PRO Handheld Thermal Imaging Camera can be used to inspect electrical and mechanical apparatus and identify potential problems, such as faulty components, before they become critical issues. This allows the maintenance team to address and correct issues without the need for extensive downtime, this, in turn, reduces costs.

The rugged, pistol grip design allows the thermographer to focus on their surroundings rather than the camera. The camera can capture a surprising level of detail with the high thermal sensitivity, allowing the smallest temperature anomalies to be isolated and displayed in a SuperResolution mode – 4x the standard resolution.

The new Exx-Series cameras from FLIR Systems are designed to help professionals detect the early signs of building issues, identify hot spots, troubleshoot electrical and mechanical systems, and prevent problems before they cause damage that leads to expensive repairs.

The E96, with a 640x480 resolution and eight-times digital zoom, is the most advanced Exx-Series thermal camera to date. It delivers improved measurement results over the greatest distance to target, so professionals can safely

diagnose electrical faults or locate hidden anomalies at very high temperatures up to 1500oC, found in harsh industrial environments such as steel mills or kilns.

FLIR Inspection Route is now offered as a standard feature on every Exx-Series camera and is complemented by the FLIR Thermal Studio Pro software with Route Creator plugin, sold separately as an annual subscription. The complete routing bundle enables professionals to create and export custom inspection and preplanned routes, ideal for large or multi-location electrical or mechanical projects.

Checking out wind turbines

The quick and efficient scanning of land, building sites and large machinery by UAS (Unmanned Aerial Systems, or Drones) presents not only a far safer method of inspection but a more effective view of operations, offering a new perspective from which issues and faults can be detected.

The smaller and significantly lighter infrared cameras are ideal for integration with UAVs. Drones with IR cameras are already in service for the oil, gas and utility industries, providing exceptional results in areas previously considered impossible to survey. Pairing aerial capabilities with thermal imaging techniques allows the inspection of PV systems in remote areas, meaning rooftops and large buildings can easily be assessed.

The first foray for drones into the renewables market was not with wind turbines, but with photovoltaic solar panels, which are highly  sensitive pieces of equipment that require periodic maintenance in order to replace or repair damaged panels, in order to improve efficiency. Employing infrared technology and high definition imagery makes it possible to find damaged cells, survey large solar farms and monitor the overall effectiveness of energy production.

The number of wind turbines used globally has grown exponentially over the last few years, and with it so has the need for efficient and safer inspection methods. A growing number of these are operating out of warranty and must be serviced more frequently to maintain productivity and avoid downtime. Preventative maintenance, by inspecting blades before a blade failure actually occurs, costs 25% less than reactive maintenance, while predictive maintenance costs 47% less. This is driving a brisk business in wind turbine blade inspections.

The role has traditionally been accomplished from the ground using simple visual inspections or by more complicated and risky techniques such as using a cherry picker, service platform, hydraulic crane or rope descent.

Commercial-grade UAVs handled by professional operators provide closer, higher-resolution imagery than ground-based alternatives and are also significantly quicker. UAVs are able to fly at an optimum distance from the structure, usually from 3 to 10m, and can circle around it to cover the whole surface area. This data can then be used in conjunction with photogrammetry software and used to build a three-dimensional model of the blade, delivering a level of accuracy and detail that is hard to achieve with manual methods. When and if repairs are needed, the team knows the exact location on the turbine. Because it is GPS enbaled, it also points to the repair's exact location.