1.1 Introduction

As ultrasonic testing (UT) consists of a range of non-destructive testing (NDT) techniques that use ultrasonic waves to penetrate materials and objects, it can be considered a non-destructive method for inspecting subsurface and, in some cases, surface discontinuities. UT involves detecting flaws in materials by propagating sound waves through them. These high-frequency sound waves are transmitted into materials to obtain data about the material, such as thickness or wall loss, or to detect discontinuities in the material. UT inspections use short pulse waves with frequencies between 0.1 and 15 MHz, although frequencies of up to 120 MHz are possible. Periodic ultrasonic inspections may reveal corrosion or growth of known flaws, preventing parts, components, or entire assets from failing. Many industries utilize UT, including aerospace, automotive, construction, medical, metallurgy, engineering, and manufacturing.