Dual element transducers, or simply "duals", are used primarily for tests involving rough, corroded surfaces. They incorporate separate transmitting and receiving elements mounted on a delay line at a small angle to focus sound energy a selected distance beneath the surface of a test piece. Although thickness measurement with duals is sometimes not as accurate as with other types of transducers, they usually provide significantly better performance in corrosion survey applications.
Dual Element Transducers
These transducers use a column or bath of water to couple sound energy into the test piece. They can be used for on-line or in-process tests, for scanned tests, or for optimizing sound coupling into sharp radiuses, grooves, or channels.
Immersion Transducers
Delay line transducers incorporate a cylinder of plastic, epoxy, or fused silica known as a delay line between the active element and the test piece. A major reason for using them is for thin material tests, where it is important to separate the excitation pulse recovery from backwall echoes. A delay line can also be used as a thermal insulator, protecting the heat-sensitive transducer element from direct contact with hot test pieces, and delay lines can also be shaped or contoured to improve sound coupling into sharply curved or confined spaces.
Delay Line Transducers
As the name implies, contact transducers are used in direct contact with the test piece. A thin, hard wearplate protects the active element from damage in normal use. Contact transducers are commonly used in flaw detection applications involving straight beam tests.
Contact Transducers
Similar in construction to contact transducers, but are designed to be used with angle beam wedges to generate sound at an angle to the coupling surface. They are commonly used for weld inspection as discussed in later sections.
Angle Beam Transducers
All transducers that are commonly used in ultrasonic flaw detection incorporate a vibrating element in a case, but their designs fall into five general categories. Select a style shown for a description.
Ultrasonic Transducers
Contact Transducers
Angle Beam Transducers
Delay Line Transducers
Immersion Transducers
Dual Element Transducers
This interactive content requires
Internet Explorer 9 or higher,
Chrome, Firefox, or Safari