Among the non-destructive testing methods for internal defects, Ultrasonic testing is the fastest and most reliable method. With this one can save on material, labour, machine cost & time, by early detection of defects at raw material stage. Portable Ultrasonic Flaw Detectors provide a very user-friendly flaw detection technique to analyze blow holes, porosity, inclusion & any types of flaws. High frequency sound waves generated by piezo electric transducers enter the object to be tested and get reflected at the interphase of defects such as cracks, blow holes, inclusions, porosities, lack of bond etc. The reflected echo is displayed in form of peaks on screen of ultrasonic flaw detector. The amplitude and position of these peaks give useful information regarding the location, shape & size of the defect.