The API QUSE Ultrasonic Testing Examiners (Sizing) certification exam addresses equipment and sizing evaluation techniques for crack height sizing. The designed procedure provides guidelines and techniques for ultrasonic sizing of planar cracks which originate at the opposite side of the scanning surface or the inside diameter. - See more at: http://www.americanpetroleuminstitute.com/Certification-Programs/IndividualCertificationPrograms/Programs/APIQUSE#tab_ExamInfo