Solution:Magnetic Particle Method: Iron fillings are spread over the weld and it is then subjected to an electric current. The fillings form pattern which are interpreted to locate surface cracks.Dye Penetration Method: The depth of a crack can be estimated by this method. A dye is applied over the weld surface and then the surplus is removed.
Ultrasonic Method: Ultrasonic sound waves are sent through the weld. Defects like flaws, blow holes etc. affect the time interval of sound transmission identifying the defect.
Radiography: X-rays or gamma rays are used to locate defects. This method is used in butt weld only.