whether the Ultra-Sonic Inspection method that?

NDT is one of the many methods used to detect the presence of discontinuities (disabled) deep, surface defects, defects near the surface (sub-surface) of equipment made of metal or alloy. These defects can be cracks (crack), disability gases, penetration is not perfect. In the welding slag inclusions, and others. The working principle is to utilize ultrasonic examination of the wave propagation of ultra-sonic transmitter released by the work piece and then the wave behind it was captured by a receiver (receiver). Received waves can be measured, the intensity, time propagation or resonance caused. So in general ultra-sonic inspection is based on differences in the intensity of the received wave, the difference in the intensity and propagation time and the difference resonance. Ultra Sonic can be used for various examinations.

Among others: 
-Detecting the presence of defects in materials.
-Measure the thickness of the material.
-Studying the structure of the material.
-Evaluation of the manufacturing process.

System used in the examination:
Contact testing 
Tests carried out by directly attaching transducer specimen surface.
Immersion testing 
Examination carried out by dipping the specimen and the transducer into the water bath.

Things that affect the inspection process:
Surface 
On an uneven surface specimen reflection will occur on the surface, so the examination is less to get maximum results.
The shape and location of defects.
In examining the shape and location of defects in test specimens that will be very influential on the outcome disability checks because not all easily identified.

sumber : letheg