Thermography’s growing place as a predictive maintenance technology

Dec. 5, 2022
Thermography and thermal imaging tools can help maintenance teams quickly and safely identify and diagnose issues with equipment.

Real-time asset health data, when used effectively, offers significant advantages over preventive maintenance approaches. Basing maintenance on a calendar or usage milestones can mean maintenance tasks are performed too frequently — or not frequently enough. Knowing what an asset needs, and how urgently, leads to improved asset availability and performance and reduced failures and downtime. By using real-time asset health data, maintenance teams can plan and prioritize their work, fix problems before failure occurs and keep all of their assets running better and longer.

There are numerous ways of collecting and measuring asset data that can provide insight into asset health and performance. Trending asset health data over time reveals patterns and makes it easier for teams to spot potential issues early on. Thermography is a key technology for identifying thermal degradation or changes in operating temperature of an asset. Another benefit of thermography is that it is non-contact, meaning that temperature data can be collected from safe distances. With moving or hard-to-reach parts, this increases worker safety. Contactless infrared cameras are also particularly beneficial in industries such as food and beverage, where monitoring processing equipment at a distance can be useful.

Thermography is a common and effective method of gathering useful data about an asset’s condition. Many teams already use thermography in their maintenance operations, making it a natural choice for teams looking to move into predictive maintenance. With thermography, they can use a familiar modality while applying a new maintenance approach.  

Key thermography terms

Thermography has a few key terms to keep in mind: 

  • Thermography: Creating images by using a thermal camera to capture the infrared radiation emitted by objects. The more radiation is emitted, the higher the object’s temperature is. Thermography makes variations in temperature visible.   
  • Infrared: Often abbreviated as “IR.” Refers to electromagnetic radiation with wavelengths longer than visible light. Invisible to human eyes.
  • Emissivity: The ability of the surface of an object to give off radiation. This quality is expressed on a scale of 0 to 1. A surface with a lower emissivity, such as shiny metal, can be harder to measure accurately than a surface with a higher emissivity.  

Applications of thermography

Thermography is best suited for finding electrical hots spots, mechanical faults and process issues. It is a modality that can be useful across many industries, asset types and concerns. It can identify a wide range of issues with many types of assets and components.

When an asset or component experiences a temperature change, that can be a key indicator that it is beginning to fail. That insight into asset health and potential failure gives teams time to plan their response so that assets or components can be serviced or replaced without interrupting production.

Electrical

Some of the electrical components or issues thermography can be used for include faulty connections in panels, fuses, motors and switchgears. Some common electrical reasons behind temperature deviations or hotspots include:

  • Unbalanced loads
  • Harmonics
  • Overloaded systems/excessive current
  • Loose or corroded connections
  • Insulation failure
  • Wiring mistakes

Mechanical 

Some of the mechanical components or issues thermography can be used for include motors, shafts, bearings, couplings, hydraulic pumps and misaligned belts. Some common mechanical reasons behind temperature deviations or hotspots include:

  • Reduced airflow
  • Power quality problems, such as unbalance, overload, or harmonics
  • Insulation resistance
  • Undersized components

Process

Some of the process components or issues thermography can be used for include tank levels, pipe integrity, steam traps, boilers and reactors, heaters and furnaces, chiller operation, faulty insulation and weld cooling observation. Some common process reasons behind temperature deviations or hotspots include:

  • Damaged structures
  • Abnormal heat flow
  • Gas or steam leakage
  • Failed components
  • Corrosion

How thermography use is changing

Use of thermography to inspect assets is widespread, with 62% of respondents telling Fluke Reliability in November 2020 that they were using thermal imaging already. Another 16% of respondents said they were planning to start using thermal imaging soon.

When an inspection with an infrared camera indicates that an asset’s temperature has changed since the prior inspection, that can prompt additional inspection to determine whether corrective action is needed. Route-based thermal imaging is most effective when repeatability is emphasized, meaning that similar images are consistently captured no matter which technician captures them. To encourage repeatability, teams can consider taking steps such as painting a line or box on the floor indicating where the technician should stand. Painting a target on the asset itself is another possibility. Consistent images make it easier to compare an asset’s temperature over time. 

Like many technologies, infrared cameras have become more accessible and affordable for maintenance and reliability teams. Thermal imaging tools come with a range of features and capabilities and can range in price from a just a few hundred dollars to several thousand dollars.

However, capturing the temperature data with an infrared device is just the first step. To get the most out of thermal measurements, the data needs to be incorporated with other asset data. In isolation, a thermal measurement is just one data point. Uploaded to a software that centralizes asset data, such as a computerized maintenance management system (CMMS), thermal measurement data can be compared to historical asset data or other key indicators. A baseline reference for each asset helps to identify any abnormalities. Minimum, maximum and average temperatures can also be captured and referenced.

With more context and analysis, an asset’s temperature data is much more useful. For example, some software allows for images to be sorted by severity. Or a trend line graph of center point temperatures from multiple images can help teams identify and understand temperature deviations. Comparing the thermal patterns of identical assets can help teams determine why one asset is running hotter or colder than the others.

Thermography-specific software features to look for include analytics such as image subtraction, isotherms and histograms.

Advances in thermography technology

Handheld thermal imagers are most commonly used for route-based maintenance and troubleshooting. Choosing the right thermal imaging camera is important. An in-focus image is necessary to be able to accurately measure temperatures. Cameras can come in fixed, manual or auto-focus varieties. Other considerations include the camera’s resolution and the distance or accessibility of the asset to be measured. Most cameras can capture both standard digital and infrared images at once.

Machine-mounted thermal imagers can collect and transmit temperature data around the clock. They do not require users to have direct access to machinery in order to collect data. Machine-mounted thermal imagers also offer the precision and repeatability of capturing data from the same location. Depending on the imager, teams can select how frequently images are captured as well as set thresholds for alarm notifications to be sent to team members any time those temperature thresholds are reached. With a CMMS, work orders can be automatically generated whenever a thermal imager detects that an asset’s temperature falls outside of the defined thresholds. Some temperature issues can be substantial enough to warrant automatically shutting down systems before bigger issues or failures result.

Once mounted, thermal imagers do not require any disruption to functioning machinery.

Predictive and proactive

Thermography can be a crucial part of a predictive maintenance program. Heat is a common symptom of equipment damage or malfunction — but do not forget that cooler-than-normal temperatures could also be an indication of a problem. Thermography and thermal imaging tools can help maintenance teams quickly and safely identify and diagnose issues with equipment.

Infrared cameras and thermal imaging sensors, paired with software, can take reliability programs further by helping teams harness asset data to trend it and gain actionable insights. With those insights, teams can plan and prioritize their responses to maximize asset availability and lifespan. Availability is one metric that can be used to measure the performance of repairable equipment. Measurable metrics are an important part of evaluating the success of any maintenance program, but especially important for teams establishing a predictive maintenance program.   

As a mechanical application and product specialist with Fluke Reliability, John Bernet works with customers from all industries to successfully implement their reliability programs. He has more than 30 years of experience in the maintenance and operation of commercial machinery. He holds a Category II Vibration Analyst certification and is a Certified Maintenance Reliability Professional (CMRP).

Michael Watson is a product application specialist with Fluke Reliability. Michael brings 30-plus years of experience in reliability, technician effectiveness and operations. He is a Certified Maintenance & Reliability Professional (CMRP), Certified Reliability Leader and is Thermal/Infrared Thermography Level II certified. Michael holds a Mechanical Engineering degree from the University of Illinois.

Fluke Reliability

www.fluke.com

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