Specialist inspection techniques

Specialist inspection techniques

Our team of level 3 NDT technicians is available to advise you on the best method for your project.

TOFD (Time of flight diffraction)
Most ultrasonic techniques rely on receiving reflections from defects, even if only from particular facets. Time of flight diffraction (TOFD) detects flaws using the signals diffracted from the flaw's extremities. When the sound strikes the tip of a crack, this acts as a secondary emitter which scatters sound out in all directions, some in the direction of the receiving probe. The time difference between the lateral wave and the diffracted signal from the flaw provides a measure of its distance from the scanned surface.

Advantages:

  • Detection and sizing of all types of embedded flaws.
  • Critical flaw sizing data for input to Engineering Critical Assessments

Phased Array
Phased array systems offer the possibility of performing inspections with ultrasonic beams of various angles and focal lengths using a single array of transducers. Software control over beam angle and focusing is achieved by application of precisely controlled delays to both the emission pulse and received signal for each element in an array of transducers. It replaces systems with many probes.

Advantages:

  • Detection of manufacturing flaws (lack of sidewall fusion, lack of root penetration, lack of root fusion, porosity, etc.), in-service flaws (fatigue cracking, stress corrosion cracking, corrosion, erosion, etc.) and parent material flaws (inclusions and laminations).
  • Rapid inspection of thick section pressure vessel welds (including nozzles), turbine disks, shafts and blade roots, welds in coarse grained materials and steam generator tubes

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