What Does Thermography Mean?
Thermography is the process of using an infrared camera to look for abnormally hot or cold areas on a component operating under normal conditions. It is a viable nondestructive evaluation technique for the characterization of corrosion in metallic materials and is the simplest of all thermal inspection techniques.
Thermography is useful for the detection of corrosion/erosion damage in plants operating at elevated temperatures. In addition, it can be used to check for fouling or internal plugging of piping systems and to check the quality of refractory linings. It can also be used for leak detection, composition changes and disbonds in laminates.
Thermography is usually referred to as infrared thermography or thermal imaging.
Corrosionpedia Explains Thermography
Using thermography, the temperature of objects can be made visible. It is a rapid, noncontact, wide-area inspection technique that is easy to interpret and that is not significantly sensitive to material curvature. Thermography is a technique that can be applied to most areas of plants, but which is particularly suited to plants operating at elevated temperatures. However, it is a surface technique, and it cannot be used to look through thick layers of lagging for defects in the underlying structure.
Types of thermography include:
- Passive thermography - The features of interest are naturally at a higher or lower temperature than the background. It has many applications such as surveillance of people and medical diagnosis (specifically thermology).
- Active thermography - An energy source is required to produce a thermal contrast between the feature of interest and the background. The active approach is necessary in many cases given that the inspected parts are usually in equilibrium with the surroundings.
Thermography inspections utilize the surface temperature distribution of an object. If the surface temperature is uniform, with no temperature variations, there is no indication of a problem. As a result, for some applications it has limitations.
Some important advantages of using thermography as an inspection method are:
- Inspection can take place during production.
- Inspection is quick and does not require physical contact.
- Results are recorded digitally.
- Costs are relatively low.