Thermal imaging is now widely integrated across civil, mechanical, electrical and industrial engineering with some 60% of professional engineers globally incorporating thermographic surveys into project management and asset maintenance.
Real-time visual temperature maps enabled by FLIR handheld and fixed infrared imaging devices today allow South African engineers to safely detect hidden defects without disrupting operations.
“Thermal imaging in engineering helps prevent equipment failures and significantly reduces diagnostic time,” says Phil Smerkovitz, Managing Director of GoThermal, an SA-based, authorised distributor of FLIR Systems thermal imaging technology.
Catastrophic engineering failures don’t happen overnight. Fortunately, thermal imaging technology has advanced to the point where a handheld camera can reveal abnormal temperature patterns long before a fault becomes visible to the naked eye.
However, the real value of thermography comes from combining professional thermal imaging equipment with trained operators.
“Thermal imaging is an incredibly powerful inspection tool, but reliable thermography in engineering depends on understanding what the camera is actually seeing,” notes Mr Smerkovitz.
There is an important distinction between capturing a thermal image and correctly interpreting one. For instance, a hotspot doesn’t always mean a fault. Surface condition, environment and measurement technique can influence the result.
Focus, emissivity, reflected energy, surface characteristics, camera resolution and inspection technique all influence what the operator sees. Understanding these variables turns thermal imaging into professional thermography.
With the above in mind, GoThermal provides guidance below on five common thermal imaging mistakes engineers will avoid when their expertise is supplemented by professional thermography training.
Always confirm focus before recording or saving a thermogram because poor focus can affect more than image quality. A poorly-focused thermal image can blur the boundaries of small components and incorrectly spread thermal information across pixels. Sharpening the image afterwards cannot recreate thermal measurement information that was never properly captured.
Understand the surface being inspected because emissivity can produce a convincing wrong answer.
Different materials emit infrared radiation differently. Painted surfaces, plastics, insulation and oxidised metals behave very differently from polished aluminium, stainless steel or copper. The thermographer needs to understand the material being inspected and its condition.
Because thermal cameras detect infrared radiation reaching their detectors, that ‘hotspot’ could actually be a reflection. Cameras do not automatically know whether radiation originated from the target or was reflected from another source. This becomes particularly important when examining smooth or shiny materials. Hot machinery, sunlight, lighting, electrical equipment or another heat source can potentially create a reflected thermal pattern on the surface being inspected.
Bare polished metal generally has low emissivity and high reflectivity meaning shiny metal can hide a serious temperature difference.As a result, measuring directly from the metal surface may produce a temperature difference that appears relatively insignificant even when a more serious thermal condition exists.
This can have major consequences when maintenance decisions are based on temperature severity.
Excellent inspection technique cannot recover detail that the camera never captured because the wrong device or lens was used. The appropriate camera therefore depends on what needs to be inspected. A wide-angle lens may be ideal for examining a large electrical panel from a relatively short distance. A telephoto lens may be more appropriate when the target is small or must be inspected from further away.
Ultimately, professional thermography requires more than simply placing a measurement cursor over the hottest-looking point. The device itself cannot determine the cause of every anomaly. Understanding by human engineering and thermographic professionals is always required.
“In the final analysis, thermal imaging shows the evidence, while thermography provides the diagnosis,” concludes Mr Smerkovitz.
GoThermal supplies FLIR thermal imaging equipment as well as providing professional thermography training in partnership with the Infrared Training Center (ITC).
Please see: www.GoThermal.co.za.
