Introduction

Phased array technology has taken the world by storm in the inspection ability to scan structures and to achieve dynamic beam focusing and beam steering without mechanically moving actuators over the part under examination. Modern-day electronics and cost reduction have inspired activity in this area. The first real-time phased array multi-element transducer system used in medical ultrasound was introduced in the ’70s with applications in solid materials following in the ’80s. In the case of using bulk wave ultrasound, only straight line computation was needed to control wave interference phenomena at selected points inside the human body or inside a specific solid structure. In addition to real-time phased array systems, synthetic focusing was introduced whereby enough information was transmitted from a multi-element array and subsequently received by the individual elements, where software was used to simulate the real-time phased array approach. Both methods provide special advantages.

During the ’90s, real-time phased array and synthetic focusing methods were introduced for cylindrical structures, primarily pipelines. The time delay computations to achieve this are more complex. This chapter primarily focuses on principles for cylindrical piping structures.