eddy current results do not correlate 1

[kckc]

Had an eddy current test on our condenser SS tubes in 2001. Results indicated 20-49% wall loss. Rechecked same tubes last week and results indicated no wall loss. I am reasonably sure the metal did not grow back. %-) What factors could account for the disparity in results? Cleanliness? Moisture? Calibration? Any ideas would be helpful.

 

[aybee]

reasons from someone with exposure but not hands -on usage of eddy current ndt
you would need to calibrate on similar material preferable a section of the same tube with a known defect
cleanliness important scale will cause odd results
operator competance?

 

[flames]

The biggest error we find in eddy current is due to the operator. We almost always stick with the same guy to do any of our eddy current or remote field eddy current.

Like aybee said above, make sure that you have a calibration tube.