What are non destructive test in welding ?

4. Ultrasonic test (UT)

In ultrasonic testing, beams of high frequency sound waves or inaudible, short sonic waves of 0.5-15 MHZ are introduced into a test object to detect and locate surface and internal discontinuities.

A sound beam is directed into the test object on a predictable path, and is reflected at interfaces or other interruptions in material continuity.

The reflected beam is detected and analyzed to define the presence and location of discontinuities.

5. Penetrant test (PT)

The penetrant test uses fluorescent or red penetrant to visualize defects such as cracks and pits that open to the surface of a weld zone. If there is any defect that is open to the surface of a weld, the applied penetrant penetrates into it.

 After it has fully penetrated the surface is cleaned with water or solvent depending on the type of penetrant. When a developing solution is applied, the penetrant left in the defect comes to the surface exhibiting an indication pattern.

The pattern is easily identifiable because it is either fluorescent (fluorescent penetrant test) or red (dye penetrant test) depending on the type of penetrant. In this test, even a minute defect can easily be detected.