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|NDT.net Issue - 2016-12 - NEWS ||NDT.net Issue: 2016-12|
Publication: e-Journal of Nondestructive Testing (NDT) ISSN 1435-4934 (NDT.net Journal)
EquPAS – the Equalized Phased Array Ultrasonic Testing (PAUT) Sensitivity approach from Sonotron NDTSonotron NDT72, Rehovot, Israel
EquPAS – the Equalized PAUT Sensitivity approach is applicable for the inspections implemented by all portable and automatic ultrasonic PA flaw detectors and systems of Sonotron NDT’s ISONIC series (ISONIC 3510, ISONIC 2010, ISONIC 2009 UPA Scope, ISONIC PA AUT) covering the welds and parent material of all types and shapes, shafts and axles, raw materials (forging and casting), composites, etc tested with the use of linear, matrix and other types of PA probes.
The EquPAS approach resolves the issue of inhomogeneous sensitivity over cross-section or volume of the material covered through implementing of the desired scan plan (either sectorial, linear, tandem, or 3D) by PA probe in each position over the scanning trace. Prior to the inspection the instrument’s PA pulser receiver is calibrated in the same manner as the regular conventional ultrasonic flaw detector for one focal law selected from the plurality to be implemented within the entire scan plan. Whilst implementing the sequence of pulsing receiving cycles following the scan plan each focal law is characterized by the individually settled focal point and time base; the sensitivity is equalized within entire insonified section of the material through use of the independent mechanisms of Angle Gain Compensation (AGC, sectorial scan) or Gain per Shot Correction (GSC, linear, tandem, or 3D scan) and DAC/TCG acting simultaneously thanks to the unique ability of ISONIC Series PA instruments: the DAC / TCG mechanism is used purely for compensating the dependency of echo amplitude on the material travel distance while the feature of varying Gain per Focal Law voluntarily is utilized just for the forming of easy-reproducible AGC (or GSC) plan. Both the DAC / TCG and AGC (or GSC) plans are created with use of the same set of reference reflectors. The color palette used for the imaging represents dB-to-DAC (TCG inactive) or the echo height (TCG active) value for each signal. As a result the same defect will be represented with the same color and evaluated accordingly independently on it’s position in the insonified cross-section or volume of the material.
The video below illustrates an example of the EquPAS approach applied to the S-Scan cross-sectional coverage with the use of most common reference reflectors (Flat Bottom Hole, EDM Notch, and Side Drilled Hole) for the sensitivity calibration.
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