Ultrasonic Testing Procedures, Technician Skills, and Qualifications

Following the Northridge earthquake, the quality and accuracy of the ultrasonic testing (UT) of structural steel connections, and the abilities of technicians to perform such testing, was drawn into question. In establishing new weld quality acceptance criteria and appropriate inspection guidelines, it was important to validate the ability, or lack thereof, of ultrasonic testing technicians to accurately characterize and locate weld flaws in a variety of welded joint types. Round-robin testing of mock-up specimens representative of a variety of common joints used in steel moment frames, fabricated with embedded discontinuities of known size, location, and orientation, were examined by a number of ultrasonic testing technicians. The inconsistencies noted in the test results indicate a need for more specific UT procedures when used for weld acceptance, and a need for validation of the skill level of the UT technicians in their ability to perform the inspections.