Ultrasonic Phased Arrays for the Inspection of Thick-Section Welds

Ultrasonic phased arrays will eventually replace conventional ultrasonic methods in many nondestructive evaluation (NDE) applications. However, the transition to phased arrays is not without its pitfalls and challenges. In this report we present a summary of the advantages and limitations of phased-array ultrasonics in NDE, with specific reference to the inspection of thicksection welds. The main advantages offered by phased arrays over conventional systems are increased sensitivity, coverage and speed. The main disadvantages are that (i) phased-array systems are more expensive to purchase, (ii) operation and data interpretation are more difficult and (iii) there can be greater difficulty in achieving good ultrasonic coupling due to the larger probe dimensions. Whilst proper training can overcome the majority of these disadvantages, the main obstacle to a faster uptake of the technology is the lack of widely accepted inspection standards and calibration blocks applicable to phased arrays.