Ultrasonic testing, UT is

• a frequently prescribed testing method for seamless tubes.
• not suitable for inspection of austenitic welds because the residual solidification structure is relatively coarse and giving echoes that interfere with the evaluation
• occasionally required on welded heat exchanger tubes, in spite of its unsuitability
• performed on sheet-welded tubes as a method of inspecting the sheet edges
• normally limited to plate with a thickness > 5 mm.
• usually carried out manually and therefore expensive