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838 views
03:22 Apr-15-2006
Mohiuddin
IR-192 for High Thickness

Did anybody used Ir-192 for steel thickness in the range of 76 mm weldment? If so can you pls tell me how good was the quality. If you have a special technique in this regard pls help me.

regards
Khaja


 
08:04 Apr-16-2006
Daniel H Rice
Re: IR-192 for High Thickness ----------- Start Original Message -----------
: Did anybody used Ir-192 for steel thickness in the range of 76 mm weldment? If so can you pls tell me how good was the quality. If you have a special technique in this regard pls help me.
: regards
: Khaja
------------ End Original Message ------------
I have used IR192 in situations up to 3 inches of steel and stainless.
Exposure times increase tremendously, how ever you must consider that the "object" as described in astm E94 increases in thickness. To acheive a good films. Exposure, you must increase "Object to source" distance. faster films help but you loose contrast, i have used rare earth screens and Photo senstive films like the medical industry and .015 copper filters placed between the object and the film but not in contact with the film.Then placed a rare earth screen incontact with the film. Using this method i halfed the exposure time, and pulled .01t at a ug of .020in.
Experiment there are many products that can speed your exposure time and keep your quality high


 
07:22 Apr-17-2006

John Brunk

Engineering, NDT Level III
Self employed, part-time,
USA,
Joined Oct 1999
158
Re: IR-192 for High Thickness ----------- Start Original Message -----------
: Did anybody used Ir-192 for steel thickness in the range of 76 mm weldment? If so can you pls tell me how good was the quality. If you have a special technique in this regard pls help me.
: regards
: Khaja
------------ End Original Message ------------

In my experience this is close to the upper limit for radiography with a 100 curie Ir-192 source. Exposure times can certainly be very long, and keeping the source and film stable can be a problem if there is a possibility of vibration or shocks in the area. However, both image sharpeness and contrast are notably better than with Co-60. If you are able to use solid-state radiography instead of film that will shorten the exposure time a lot. It is a good idea to perform ultrasonic examination in addition to radiography. I have had the experience of repairing a defect found during initial radiography with Co-60, then when the repair region was re-inspected finding additional defects with both Ir-192 and ultrasonic testing.



 


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