Ultrasonic phased arrays use multiple ultrasonic elements and electronic time delays to create beams by constructive and destructive interference. As such, phased arrays offer significant technical advantages over conventional single-probe ultrasonics; the phased array beams can be steered, scanned, swept and focused electronically.

Figure 1: Schematic showing generation of linear, sectorial and focussed scans using phased arrays.

ADVANTAGES

• Speed: scanning with phased arrays is much faster than single probe conventional mechanical systems, with better coverage;
• Flexibility: set-ups can be changed in a few minutes, and typically a lot more component dimensional flexibility is available;
• Inspection angles: a wide variety of inspection angles can be used, depending on the requirements and the array;
• Imaging: showing a “true depth” image of defects is much easier to interpret than a waveform. The data can be saved and re-displayed as required.
• Safety: No special safety requirements as in radiography. 
• ASME Code Compliant: Phased arrays can be used in lieu of radiography, as per ASME code case 2235.

APPLICATIONS

Realistically, there is no “typical application” for phased arrays; phased arrays are very flexible and can address many types of problems. Consequently, ultrasonic phased arrays are being used in a wide variety of industries, where the technology has inherent advantages. These industries include: aerospace, nuclear power, steel mills, pipe mills, petrochemical plants, pipeline construction, general manufacturing and construction, plus a selection of special applications. All these applications take advantage of one or more of the dominant features of phased arrays.

TYPICAL EXAMPLES OF PHASED ARRAY INDICATIONS