RT

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Title:	RT
From:	William Blum
Email:	wblum@brighttechnical.com
URL:	http://www.brighttechnical.com
Added:	7/5/2001 11:30:20 PM
Message:	ASME Section V recommends minimum thickness limits for radioactive isotopes but states "The maximum thickness for the use of radioactive isotopes is primarily dictated by exposure time therefore upper limits are not shown." I suggest you shoot a test shot or two and see if you are achieving the required sensitivity. If so, it is a matter of the time necessary to make the shot. You can also post your question here http://www.ndt.net/wshop/forum/forum.htm and here www.asnt.org.

density is time linear
Posted:
9/23/2002 9:13:29 PM

Subject: time adjustment

While adding time will increase burn, scatter exposure, and decrease sensitivity somewhat, a simple adjustment in time as opposed to the inverse square law is far quicker and fairly accurate in field radiography. Quite simply if a one minute exposure gives a 1.0 reading, a 3 minute exposure will achieve a 3.0 density. The longer the exposure the less linear the time /density curve is constant, with the exposure acquiring a slighter higher % of density in relation to time, meaning if a 5 minute exposure produces a 1.0, a 15 minute exposure may produce a density reading slightly higher than 3.0 However this is incredibly accurrate with x-ray machines, both low and high energy, which can save time in developing techniques.