Techniques vary due to weld material, weld thickness, weld process and even code requirements.
An advance in ultrasonic weld inspection was in the 1970's with the introduction of Time of Flight Diffraction. TOFD was a response to the demand for better sizing of defects, however, the technique have its limitations if used for defect detection - it cannot detect all defects. An ultrasonic technique for weld inspection should investigate the total weld volume plus a region either side of the weld considered to be the heat affected zone. Since laminates can be present in the base material, that means under the coupling surface, it is essential that a simple straight beam test is performed for inspection of laminates. Usually shear waves angle probes are applied as single probe, douple probe, tandem, pitch and catch techniques.