Ultrasonic Inspection

Ultrasonic inspection is fast, reliable NDT method which employs electronically produced high frequency sound waves that will penetrate metals, liquids and many other materials at speeds of several thousand feet per second. Piezo electric materials (e.g. quartz) are used to produce ultrasonic waves. (These materials undergo a change in physical dimension when subjected to electric field. This conversion of electrical energy to mechanical energy is known as Piezo electric effect).

If an alternating electric field is applied to a piezoelectric crystal, the crystal will expand during the first half of cycle and contract when the electric field is reversed. By varying the frequency of the alternating electric field, we might vary the frequency of the mechanical vibration (Sound Wave) produced in the crystal. There are two common Ultra sonic test methods, the through- transmission & the pulse-echo methods. Ultrasonic inspection is utilized to detect and locate defects such as shrinkage in cavities, internal bursts or cracks, porosity and large non-metallic inclusions. Wall thickness can also be measured in closed vessels or in cases where such measurement cannot otherwise be made.