Vietnam
Posted:
7/5/2001 7:03:31 AM
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Email: thoinh@yahoo.com
Subject: radiographic testing for spherical tank
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firstly, thank you very much for your interest in this page.
My name: Nguyen Huu Thoi
My occupation: RT, UT, MT, PT inspector level II.
Now, my company have a job: Dung Quat Refinery project. In this project, there are 6 spherical tank need to carry out RT. So the thickness is very large: 55 to 80mm.
In Vietnam, RT equipment used: Gamma Source Ir 192, film used : AGFA D4/D7 or Kodak AA. I think that with this equipment and facilities, can not carry out RT for the above-mentioned, the film quality is too bad.
So i send this page to every body that how to carry out NDT for this job.
Once againe, thank you for your help.
Regards
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William Blum
Posted:
7/5/2001 11:30:20 PM
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Email: wblum@brighttechnical.com
Subject: RT
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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.
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density is time linear
Posted:
9/23/2002 9:13:29 PM
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Subject: time adjustment
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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.
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