Non destructive measurement of thickness

Replacing the ultrasonic method by multi-frequency eddy current methodSciensoria sarl 35170 BRUZ – www.sciensoria.fr info@sciensoria.fr

Why measure the thickness of a tube ?

•

How to measure the thickness of a tube ?

• Classical method by contacts

• Non destructives– Ultrasonic method ⇒ need of coupling liquid– Ionizing radiation(X, γ) ⇒ dangerous,

expensive

• And now, multi-frequency eddy current– no coupling liquid, rapid, easy to deploy– a green testing method !

Eddy current NDT, what's new?• Old technique invented in the XIX century, popular after

1945• Main applications:

– Flaw detection, materials sorting– Thickness measurement: requires calibration on standard – Sensitive to material changes– Material changed ⇒ new calibration ⇒ delay, cost

• New: multi-frequency eddy current technique– Eliminates changes of the material – High precision for low thickness values– Easy and quick deploy

How does it works?• Multi-frequency technique, rich in information• Powerful model-based analysis of signal• Fast and precise digital instrument

Advantages• Automatic recognition of target material, self

adaptive– Measures simultaneously the electric conductivity σ

• Rejection of effects of poor positioning of the probe:– Eccentricity– Tilt

• Fast measurement– Measurement time ≤ 1,5s for an unknown probe, …

much more shorter if the tube material well known and the probe is well fixed

Ultrasound/Eddy current Comparison • Measurement on four generatrices of a tube: with 1 point calibration, the

multi-frequency eddy current method is as accurate as the ultrasound method

Conclusion• Multi-frequency Eddy current: does not

require calibration, can measure the absolute value of the thickness

• Ultrasound vs Multi-frequency Eddy current : same precision with 1 point calibration

• Multi-frequency Eddy current : no coupling, easy positioning, precise for low thickness, easy deployment

• Eddy current wins

For more details

• Internet– http://www.sciensoria.fr– http://www.sciensoria.com

• Demo Videos on Youtube– http://youtu.be/WC5suY4gcqU – http://youtu.be/CN5WH1Tl9ps