Thermal Imaging Guide
Thermal imaging reveals problems invisible to the eye: loose connections, overloaded circuits, and failing bearings. Learn how to use thermal cameras for predictive maintenance.
What Thermal Imaging Reveals
- Loose electrical connections: A loose connection has higher resistance, generating heat. A thermal camera shows the connection as a hot spot.
- Overloaded circuits: Cables, breakers, and fuses running above their rated current heat up. Thermal imaging identifies which circuits are running hot.
- Failing bearings: A bearing starting to fail generates friction and heat. A thermal camera on the bearing housing shows the elevated temperature.
- Blocked cooling: Clogged heat exchangers, dirty motor fins, or blocked cooling paths show up as hot areas because heat can't dissipate.
- Steam leaks: Steam leaking from a valve or trap is hot. Thermal imaging can locate leaks in insulated piping where they are invisible.
- Refractory damage: Cracks or degraded refractory in boilers and furnaces allow heat to escape. The thermal camera shows the exterior hot spots.
How to Perform a Thermal Survey
- Survey during normal operation. Equipment should be running at typical load for meaningful results.
- Remove covers and panels where safe to expose connections and components. Follow arc flash safety procedures.
- Scan each component. Compare similar components (e.g., three phases of a breaker) side by side. Temperature differences are more significant than absolute temperature.
- Save images with location and equipment identification. Use the camera's annotation features.
- Flag any component with a temperature 10 degrees C or more above similar components, or above 60 degrees C for electrical connections.
- Generate a report with findings, prioritised by severity.
- Schedule repairs for flagged items. High-priority (large temperature rise, critical equipment) first.
- Re-scan after repairs to verify the fix.
Interpreting Thermal Images
- Electrical connections: A temperature rise of 10 to 20 degrees C above a similar connection indicates a loose or corroded connection. Schedule tightening or cleaning. Above 30 degrees C is urgent.
- Breakers and fuses: A hot breaker or fuse is carrying too much current or has internal resistance. Investigate overload condition or replace the device.
- Bearings: A bearing 10 to 15 degrees C above a similar bearing indicates developing problems. Check lubrication and vibration. Above 25 degrees C is urgent.
- Motors: Uneven heating (one end hot) indicates a problem at that end (bearing, winding, cooling). Generalised overheating indicates overloading or inadequate cooling.
Thermal imaging is non-contact
Thermal imaging can be performed without touching or disturbing equipment. This makes it ideal for surveying energised electrical panels, hot piping, and rotating equipment. But always follow electrical safety procedures. Removing panel covers on energised switchboards requires appropriate PPE and training.
Tip: Perform a full thermal survey of the plant annually at minimum. For critical equipment (main switchboard, large motors, transformers), survey quarterly. PlantLogica can store thermal images with asset records and schedule survey reminders.