5 Common Types of Non-Destructive Testing Methods You Must Know About

In most manufacturing processes and in-service inspections, Non-Destructive Testing (NDT) or Non-Destructive Evaluation (NDE) is used to analyze product integrity and performance without causing it any kind of damage. It helps monitor manufacturing processes, reduce operation costs, and maintain quality. It’s commonly used in industries such as aircraft, spacecraft (shuttle), automobile, power stations, oil refineries, buildings, and many others.

Today, many NDT methods are used to test the properties of a material, part or system. Among all the methods, some are volumetric (used to spot defects or flaws that would not be visible without cutting into the component), while others are categorized as surface only. In this article, you are going to learn about the 5 most common NDT methods that most NDT Level III services use. Let’s look at them:

Liquid Penetration Testing 
This method is used for the testing of products or components built using non-magnetic metals such as austenitic-chromium stainless steel and several others. In this method, a liquid penetrant dye is placed on the surface of the component to sweep into the metal surface, passing through the flaws. The liquid used has low viscosity, which helps find defects in the surface. This is a straightforward and cost-effective method to locate any cracks or abnormal porosity on the surface of metal equipment.

 
Magnetic Particle Testing 
Magnetic particle examination is done to find surface or near-surface flaws in ferromagnetic materials like carbon steel. To carry it out, the metal is magnetized using a permanent magnet, electromagnet, or by running a current through it. The air gaps because of defects or cracks on or near the surface show leakages in the magnetic flux. Iron particles or any fine particles of a magnetic material is used to detect those leakages. 

Ultrasonic Testing 
This is a volumetric NDT Level III services method used to find minute flaws within the metal without the need to cut it. In this, ultra-high frequency sound waves are generated through the material with the help of a transducer. When the sound waves touch any discontinuity or imperfection, they get reflected toward the receiver and then, they are measured to display on the screen.
 
Visual and Optical Testing
It is one of the essential inspection techniques of non-destructive testing. In this method, an inspector uses special tools such as magnifying glasses, borescopes or mirrors to gain access to the surface of the component and closely inspect the subject area. It requires adequate illumination of the subject surface and proper eye-sight of the inspector to perform a precise inspection.

Radiographic Testing 
It’s a common NDT method that utilizes either x-rays or gamma rays to analyze the internal structure and integrity of the manufactured component by identifying any flaws or defects. NDT Level III services use this technique to locate discontinuities that are present on the surface.

Though there are several other NDT methods used for the testing, these are the most common ones. Only NDT Level III services know how to implement these testing methods for precise results. 

About This Author

NDT Consulting Services Inc. https://www.ndtcs.com/ Joined: February 24th, 2019