What is Non-Destructive Testing?

Examining structures and materials without doing them any damage can be a challenge. How can you tell what is inside something without breaking it open to see? In all kinds of construction or material analysis fields, it is a common problem. It's led to the creation of a whole new field known as non-destructive testing (NDT), and there is a range of NDT equipment on the market.

How Does It Work?

Well, there are a whole range of potential tests and methods involved in NDT, so there is no single explanation about how it works. And to the novice, it can be a pretty complex field.

Ultrasonic or radar-based methods use sound waves to examine structures and materials to "see" beyond the surface and to detect possibly flaws in the material. This is a very helpful technique to see what's inside the material of a structure (like within a wall or under a floor). X-ray generators can also be used for this kind of deep scanning.

Liquids can be used to find cracks or defects in any material, without doing any damage. A traceable liquid is applied, and it will accumulate in any cracks that are otherwise to small to see. This technique is particularly common in testing metal welds.

There are also ways of using magnetism to determine information about metal components without having to take samples, and thermal imagery can use temperature to test for stresses in materials or assess heat leakage.

One last type of NDT is known as eddy current testing, and though it sounds like it involves liquid, it actually uses electromagnetic currents. By monitoring the movement of these currents over the surface of a material, you can detect flaws, cracks or other problems.

These are just a few examples of methodology that can be used for NDT. Some techniques are difficult to describe, and some are very specific to a certain type of task. Don't be surprised if all this material is new to you.

You can even see some basic NDT concepts in medicine. Procedures that we are familiar with, such as X-rays, magnetic image resonance (MRI) and radiography are all vital tests that don't involve any invasive or damaging techniques.

The engineering principles involved in NDT aren’t really easy to understand for the layman, so don't expect all of the details to be crystal clear if you are a typical homeowner. In fact, you will likely want to deal with someone who is officially certified in this kind of service for that very reason. Just because this kind of testing and scanning doesn't do any damage to the structures involved, it doesn't mean it's perfectly safe for the untrained to handle the equipment. X-rays, electromagnetic currents and even radioactive materials can be part of NDT and be quite dangerous if not used properly.

So next time you have a construction project and need to do a little investigation that goes beyond the visible surface, you might want to consider some NDT options.