Hey bonnieweldor!
You might want to first learn how to spell the word "query" instead of "querry" before you start calling persons who frequent this forum "UT Dweebs"!!! More than one of these extrordinary individuals want to share their wide range of knowledge and experience in order to pass it on to anyone that want to learn more about this method of NDT.
Respectfully,
SSBN727 - Run Silent... Run Deep!!!