Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers



Last updated: November 3, 2016

What Does Wedge Mean?

Wedges are an important component of the probes used in phased array technology. Phased array probe assemblies are usually provided with a plastic wedge. Wedges are used in longitudinal wave and shear wave applications.

The function of the wedges is essentially the same as that of phased array systems, where conventional single element flaw detection is performed by coupling sound energy from a transducer to a test piece so that its mode converts and refracts at a pre-determined angle according to Snell’s Law.


Corrosionpedia Explains Wedge

Wedges can be custom contoured to accommodate complex part geometries. In addition to incident angles, there are several wedge dimensions that are used in programming phased array scans to ensure the proper distance and depth calibration and the proper refracted angle.

The sound energy is coupled by zero degree wedges (which are flat plastic blocks), for protecting the transducer face from scratches or abrasion in straight linear scans and also for low angle longitudinal wave angled scans.

Phased array systems also have an ability to steer a beam at multiple angles from a single wedge. This refraction effect of steering the beam at a particular angle is a part of the beam generation process. Shear wave wedges appear similar to those used with conventional transducers, and like conventional wedges they are available in many size variations. Some of them incorporate couplant feedholes for scanning applications.

Some key points of wedges:

  • Available in multiple refracted angles of zero, 45, 55 and 60 degrees in steel.
  • The hand skewing movement with the lateral wedges is replaced by lateral electronic scanning.
  • The user has the flexibility to design and manufacture the wedges at any desired refraction angles.
  • Wedges can perform both types of scans – manual or automated.

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