Ultrasonic Inspection

How it works

A probe introduces short pulses of high frequency sound into the part through a couplant. The sound travels until it meets a change in acoustic impedance, at which point some of it reflects back. Timing those reflections gives the depth of whatever caused them, and their amplitude, assessed against a calibration reference, gives an indication of size. The result is usually read as an A-scan trace, with the back wall echo confirming that sound has reached the far side of the part.

What it detects

Internal discontinuities of the kind that no surface method will reach: cracks, lack of fusion and lack of penetration in welds, laminations in plate, inclusions and shrinkage in forgings and castings, and porosity. The same technique measures remaining wall thickness where corrosion or erosion is the concern.

Typical applications

Weld examination in structural and pressure fabrication, forging and casting inspection, corrosion and thickness surveys on in-service plant, and bar and billet inspection in production.