Flaw detection is the primary focus of all nondestructive testing (NDT) inspections. But before we dive into actual flaw detection, we need to have a solid understanding of what a flaw is. The term has been the subject of many discussions and debates within the NDT community for years. In fact, as recently as only a few years ago, you could find several different definitions of flaw, across many NDT procedures and specification glossaries. It was even defined differently within ASNT’s own NDT glossaries for various methods. The Ultrasonic glossary defined it as “an anomaly or unintended discontinuity” while the Visual glossary stated it was a “rejectable anomaly.” So, these inconsistent definitions have caused much confusion and have led many to use the terms indication, defect, and discontinuity as interchangeable words for the term flaw. But, in reality, this is not correct. The proper definition of a flaw is “an indication which is determined to be a discontinuity, but does not exceed rejection limits.” Once a flaw exceeds rejection limits, it becomes a defect.