Non-destructive testing is the process of inspecting, testing, and evaluating materials to find discontinuities or differences in material properties without compromising serviceability. In other words, when the inspection or test is complete, the part is fully usable.
Non-destructive tests cover a wide range of tests:
Visual Testing
This method is the most basic, elementary and usually the simplest non-destructive test method. In this method, the appearance of the piece is visually evaluated, and sometimes cameras are used to test the surface of the piece. Defects of the part are evaluated visually.
Radiography Testing
In this test, gamma and X-rays, which are capable of penetrating many materials, are used to evaluate parts and diagnose defects. In this method, after shining and passing X-ray or radioactive to the piece, the image formed on the film is interpreted and the location, size and type of defect are determined.
Magnetized Testing - MT
In this method, defects are detected by spraying iron particles on a material with magnetic properties and induction of a magnetic field. Any deformation or distortion in the magnetic fields arises from the defects in the sample and thus the defects are identified.
Ultrasonic Testing – UT
In this method, high frequency and low amplitude ultrasound waves are used to evaluate the components. After the waves collide with the fractures, the waves are received by the sensor and the thickness and type of defects are detected.
Liquid Penetrant Testing – PT
In this method, the surface of the part is coated with a colored or fluorescent penetrant. After a while, this liquid penetrates into the cracks and surface cavities of the piece. The liquid is then removed from the surface of the body and the appearance material is sprayed on the surface. The difference in the brightness of the penetrating and visible liquid makes surface defects easily visible.
Electromagnetic Testing - ET
In this method, defects are detected using a variable magnetic field in a conductive material, in which a vortex electric current is induced and this electric current is measured. The presence of ruptures and defects such as cracks in the material causes an interruption in this flow. therefore defects are identified.
Leak Testing - LT
Different methods are used to detect leaks in pressure vessels and suchlike, the most important of these are: Electric earphones, pressure gauge, gas or penetrating barrier, halogen diode, mass spectrometry as well as soap bubble test.
