Swiss Approval International offer NDT services with Echo Sounding Technique, as an alternative to Phased Array UT.

This approach is often seen by other reputable Global Petrochemical asset owners (Onshore & Offshore), as a more economical and rapid means of covering large inspection areas (m2) to reliably identify the most critical defect areas.

In this way (other than small calibration reference points), UT checks (A-scan or PA) need only be carried out to confirm the minimum remaining thickness at the worst areas identified.

Case Study: Evaluating the structural integrity of a Column during operation example

  • An On-stream, High Temperature Wall Thickness Measurement survey was carried out on a refinery Tower during operation. This inspection was performed using Electromagnetic principles based on Echo Sounding Technology.
  • The advantage of applying this method is that it can gather average wall thickness information without taking the Column Off-line or removing the insulation. Provided that a known thickness reference point can be used for calibration, the test results can be used for monitoring purposes and repeat tests compared to identify any deterioration trends at any stage.
  • The surface operating temperature of the Column would be in excess of 280˚C at the elevation to be tested.
  • The 150mm of external insulation under a thin aluminium cladding protection
  • The nominal thickness was 21.0mm, but the selected Reference Point for calibration purposes was known to be 20.6mm.
  • Corrosion allowance 6.0mm.

Calibration was taken from one specific Reference Point at a location of known thickness as advised. All other readings were then compared with this value.







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