where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

329 views
Technical Discussions
Eli Brosh
Eli Brosh
09:43 Mar-23-2007
ECT-limiting frequencey for cylinder and tube

In Eddy current testing, the analysis of impedance diagrams is simplified by use of normalized frequency. That is, by using a ratio of the actual frequency used and the "limiting frequency" fg.
In the ASNT handbook, I found the following formulas for fg (in non-ferromagnetic material):
1. for cylinder in an encircling coil: fg=a/(sigma*D^2)
2. for tube in an encircling coil: fg=a/(sigma*D*W)

Where a is a constant whose value depends on the units used, sigma is the conductivity, D is the diameter of the cylinder or the outer diameter of the tube and W is the tube wall thickness.

Strangely, these two expressions do not coincide when W=D/2, that is when the tube becomes a full cylinder.
Have I missed something here /
Does formula 2 have a limited range of application so that it does apply when W=D/2 ?

Thanks
Eli


 
 Reply 
 

Product Spotlight

FMC/TFM

Next generation for Phased Array UT is here now with FMC/TFM! Have higher resolution imaging, impr
...
oved signal to noise ratio, characterize, size and analyze defects better with access to several wave mode views and save raw FMC data for higher quality analysis.  Some of the benefits are:
  • Beautiful Image! Easier to understand what you're looking at
  • Completely focused in entire image or volume
  • Much easier to define setups before inspection
  • Easier to decipher geometry echoes from real defects
  • Oriented defects (e.g. cracks) are imaged better
  • See image from different wave modes from one FMC inspection
  • FMC data can be reprocessed/analyzed without going back to the field
>

HARDNESS TESTER TKM-459CE combi

TKM-459CE combi applies 2 methods of hardness control: UCI and Leeb. It provides high-accuracy tes
...
ting of metals and alloys as well as items of different sizes and configurations, their hardened layers and galvanic coatings. Device represents results in HB, HRC, HV and others. Shock-, dust- and water-proof housing with intuitive software make this gauge easy to use in all working conditions.
>

Combination of Digital Image Correlation and Thermographic Measurements

The combination of measuring results from the digital image correlation (ARAMIS, DIC) and temperat
...
ure measuring data from infrared cameras permits the simultaneous analysis of the thermal and mechanical behavior of test specimens in the materials and components testing field.
>

GUL Subsea Solutions - Screeening & Monitoring

To inspect new and existing subsea lines, you need proven technology and experience. GUL offers it's
...
technology to solve this challenge: GUL Subsea and gMAT Transducer Rings.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window