Ultrasonic Testing (Area Coverage)

[bmoorthy]

This is related to Automatic Plate Ultrasonic testing using pulse echo method, A scan. Plates move on the roller and Multiple probes are mounted in a row and scan the plates (along the rolling direction).

I would like to know whether a normal probe (0 degree) covers more area while scanning, as compared to TR probe, assuming all the other parameters remain the same including the diameter of the probes. Especially, when the split line seen in the TR probe is oriented along the scanning direction.

The crux of the question is, if there is a Normal probe of a given diameter and TR probe of the same diameter then, is the effective scan area the same for both TR probe and normal probe or is the effective scan area different?

 

[NDTLevel3]

You should probably check with your probe manufacturer. However, generally speaking, the crystals in TR probes are set in at an angle thereby "focusing" the beam at a certain depth and reducing the amount of beam spread. Normal probes with one crystal have more beam spread at a given depth so will provide more coverage.

William E. Blum
Manager
NDT Consulting Group Inc.

http://www.ndt-cgi.com

wblum@ndt-cgi.com
USA 1-877-638-2441
Fax/Voice Mail 1-214-853-5131
Sweden 46-42-14 39 99

 

[bmoorthy]

Thankyou

Just hypothetically speaking if the defect is in the out side of the beam cone but within the diameter of the probe then also the probe would not detect, am i correct.

What is the general convention as regards the angle of inclination in a TR probe(Just an example would do), so that i could calculate the actual coverage area.

 

[NDTLevel3]

If no sound hits the defect, no sound is reflected back therefore no detection. The angle of inclination varies with the probe design so you need to contact the manufacturer of your transducer to get the specifics. To learn more about transducer and UT in general visit this site

http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Introduction/description.htm.

William E. Blum
Manager
NDT Consulting Group Inc.

http://www.ndt-cgi.com

wblum@ndt-cgi.com
USA 1-877-638-2441
Fax/Voice Mail 1-214-853-5131
Sweden 46-42-14 39 99

 

[TTT]

Low frequency - less beam spread
Higher frequency - more beam spread
Bigger diameter - smaller beam spread
As William explained, twin crystal probes are focussed but still have some beam spread, although this depends on depth or distance from probe.
In plate, automated UT is not overly sensitive, they are usually scanning for thickness, laminations, inclusions.
Hope this helps