For years prior to the advanced techniques of PAUT and TOFD, ultrasonic flaw detection was performed using one or more combinations of UT technique variables. Contact or immersion, pulse echo or through-transmission, straight beam or angle beam. Many Codes and standards still prescribe these tried and true techniques for specific applications
Ultrasonic flaw detection is exactly what it's name implies. Depending on the material/item configuration, location and orientation of suspected flaws and the Code/standard/specification requirements, a technique can usually be developed to provide the required examination.
Angle beam examinations are typically performed on welds, some tubular products and forgings as prescribed. Straight beam is used to examine plate for laminations, castings, forgings, shafts and in some instances, welds.