Phased Array Ultrasonic Testing of Stainless Steel Pipe Welds

Weld inspection of stainless steel pipes and pressure vessels is one of the most challenging and difficult inspections for ultrasonic testing. This is due to variations in grain structure and associated anisotropy. Anisotropy causes grain scattering and adversely affects propagation of sound waves. The effect is more telling for shear waves, which, in many cases, have almost no ability to penetrate the weld volume. Longitudinal waves are affected to a lesser degree by anisotropy and can be applied for such tests. Angle beam or refracted longitudinal waves are, therefore, the accepted method for stainless steel weld inspections.