Published on 02-Mar-2024

Power of Thermography Testing: A Non-destructive Approach

Power of Thermography Testing: A Non-destructive Approach

Table of Content


In the realm of Non-destructive Testing (NDT), where the quest to unveil hidden flaws and ensure the integrity of critical components is paramount, one method stands out as a true marvel of modern engineering: Thermographic Testing.

Thermography Testing in NDT is a method that doesn't rely on physical probes or invasive procedures but instead harnesses the power of heat and the keen eye of thermal imaging.

Thermographic Inspection is a Non-destructive Testing Method that involves visualization of heat radiations from an object and the method is a non-contact inspection technique. 

It is also simply called IR – Infrared Thermography Inspection, Thermal Imaging technique, or Thermography.

Fundamental Principles of Infrared Thermography Testing

Principles of Infrared Thermography Testing

Infrared testing Non-destructive Testing is based on the principle that every object emits infrared radiation (heat) proportional to its temperature.

While this radiation remains invisible to the naked eye, thermal cameras can effectively capture and detect it.

The sensors in Infrared Thermography NDT capture Infrared radiation from any object above absolute zero temperature (-273.15°C), and display heat distribution images on screen.

Defective areas emit more heat due to more heat distribution around the defects.

What is an Infrared Wave?

Infrared Wave

Infrared waves are a type of Electromagnetic Radiation like Light Radiation that is not visible to human eyes, because of their longer wavelength.

The wavelengths that are longer than the wavelength of red light (i.e. 700 nm) are called Infra-Red (i.e., That of inferior Frequency than Red Light),

The amount of Infrared Radiation captured in Thermography NDT is equal to the heat dissipated from that area, therefore Infrared cameras can be used to capture images of heat distribution.

Infrared and vibration inspection are versatile Non-destructive Testing Techniques with applications across various industries, helping to improve safety, energy efficiency, and the overall reliability of systems and structures.

Its non-invasive nature and ability to reveal hidden problems make it an invaluable tool in preventive maintenance and quality control.

Types of Thermography Inspection

Thermographic inspection can be broadly categorized into the following categories based on the source of thermal excitation.

They are as follows:

1. Passive Thermography

  • Infrared Thermography
  • Tetra Hertz Thermography

2. Active Thermography

  • Pulsed Thermography
  • Lock-In Thermography

3. Flash Thermography

4. Vibro-Thermography

Thermal Inspection Classifications Explained as Follows:

1. Passive Thermography

This NDT Method involves scanning the component during its operation or Immediately after the operation (e.g. Running motor shaft), It does not require an external heat source for heating, it uses the heat generated in the material during its operation.

Passive Thermography

2. Active Thermography

This method requires an external heat source to heat the component and monitor the flow of heat inside the material.

3. Flash Thermography

This method uses flashes of light, to identify the discontinuities that obstruct the flow of heat inside the material.

Flash Thermography

4. Vibro-Thermography

This method uses an acoustic sound source, and a thermography sensor to detect the heat distribution inside the material, the acoustic sound vibration causes more heat at the edges of cracks due to friction during vibration.

Applications of Thermography

Thermography Inspection, a technology that entails the capture and analysis of thermal images, finds extensive use across diverse industries owing to its capability to identify temperature discrepancies and irregularities.

  • Electrical Inspections

In the electrical industry, a Thermography test is used for overheating detection for components in electrical systems such as circuit breakers, switches, and wiring.

These hotspots can be early indicators of potential failures, enabling preventive maintenance.