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Technical Discussions
Marc Trepanier
Marc Trepanier
01:12 May-02-1999
Re: Gamma Exposure Calculation Needed

There are two reference sources that might help

ASNT NDT Handbook Edited By Robert C McMaster chapter 15.28 could aid you or use the Radiographic exposure calculator that can be purchased through any reputable NDT society.

Hope this helps

Hi,
we are also looking for a equation for Ir 192 and Co 60. We are looking for
a program for RT. We want it for castings, it means for different
wallthickness and multi films maybe.
But nobody knows such a equation (we asked AGFA and FUJI)

herbert

On Wed, 28 Apr 1999 13:00:21 GMT, cargill@netxn.com (Scott Cargill) wrote:

>On Wed, 28 Apr 1999 21:34:46 +1200, "Tim Nugent"
> wrote:
>
>>Hi there,
>> does anyone have a equation for working out Gamma exposures?
>>Any help is welcome thanks.
>>
>> tim
>



    
 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1254

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1254
05:30 May-02-1999
Re: Gamma Exposure Calculation Needed
Some years ago I made a DOS based programme called the Radiographic Problem Solver.
This is a free download off the www.NDT.net
go to
http://www.ndt.net/publicat/bibliog/pss.htm
In this programme there is an option to do double film exposure.
I made no allowance for the reduction in backscatter
contribution of the lead screen due to the double film
but I think it may be of some help.

Ed


: There are two reference sources that might help

: ASNT NDT Handbook Edited By Robert C McMaster chapter 15.28 could aid you or use the Radiographic exposure calculator that can be purchased through any reputable NDT society.

: Hope this helps


: Hi,
: we are also looking for a equation for Ir 192 and Co 60. We are looking for
: a program for RT. We want it for castings, it means for different
: wallthickness and multi films maybe.
: But nobody knows such a equation (we asked AGFA and FUJI)

: herbert

: On Wed, 28 Apr 1999 13:00:21 GMT, cargill@netxn.com (Scott Cargill) wrote:

: >On Wed, 28 Apr 1999 21:34:46 +1200, "Tim Nugent"
: > wrote:
: >
: >>Hi there,
: >> does anyone have a equation for working out Gamma exposures?
: >>Any help is welcome thanks.
: >>
: >> tim
: >




    
 
 
Uli Mletzko
R & D, Retired
Germany, Joined Nov 1998, 89

Uli Mletzko

R & D, Retired
Germany,
Joined Nov 1998
89
01:22 May-03-1999
Re: Gamma Exposure Calculation Needed

On one side, everybody is free to ask everything within
this newsgroup, and the experts will try to give their
answers as good as possible.

On the other side, NDT is a serious business with high
responsibility, and it should be carried out only by
people which are within a qualification or
certification system and have passed Level examinations
according to ASNT or EN 473, e.g.


For a radiographic Level Three, with his educational
background as an engineer, it should be very simple to
take the exposure charts, which are distributed by all
major film manufacturers, and to extract the mathematic
formulas from that charts and to convert them into
small PC programs. And, of course, the Level Three has
to supply his Level Two's and Level One's with such
programs.

And, as Trepanier and Ginzel stated, exposure rulers
and exposure programs are available. Years ago,
exposure rulers were distributed for free by Varian and
by Dupont, e.g.

And, in addition, if Level Two or Level One candidates
are visiting courses of serious NDT education centers,
to my knowledge the class mates are exchanging the
available programs on their laptops.

So, for NDT people which are following the existing NDT
education and qualification system, it should be easy
to have appropriate exposure programs.

NDT beginners should not ask for the programs but
should go into the qualification system.


Best regards

Uli Mletzko

NDT Group,
State Materials Testing Institute,
University of Stuttgart,
Germany




    
 
 
Scott Cargill
Scott Cargill
07:02 May-16-1999
Re: Gamma Exposure Calculation Needed
Believe it or not you don't need to be an engineer to be a level II,
and a GOOD one at that.

I've met many Level III's that I wouldn't let touch a live source
let alone expect them to know how to extrapolate a formulae.

If it's that simple to come up with the formulae why not
take the minute or two and answer the guys question by giving him
what he asked for.

S. Cargill
asnt Tc1A level II
RT, PT, MT, UT
AWS CWI
PMI Supervisor.

: For a radiographic Level Three, with his educational
: background as an engineer, it should be very simple to
: take the exposure charts, which are distributed by all
: major film manufacturers, and to extract the mathematic
: formulas from that charts and to convert them into
: small PC programs. And, of course, the Level Three has
: to supply his Level Two's and Level One's with such
: programs.

: And, as Trepanier and Ginzel stated, exposure rulers
: and exposure programs are available. Years ago,
: exposure rulers were distributed for free by Varian and
: by Dupont, e.g.

: And, in addition, if Level Two or Level One candidates
: are visiting courses of serious NDT education centers,
: to my knowledge the class mates are exchanging the
: available programs on their laptops.

: So, for NDT people which are following the existing NDT
: education and qualification system, it should be easy
: to have appropriate exposure programs.

: NDT beginners should not ask for the programs but
: should go into the qualification system.

:
: Best regards

: Uli Mletzko

: NDT Group,
: State Materials Testing Institute,
: University of Stuttgart,
: Germany




    
 
 
Norm Woodward
Norm Woodward
03:01 May-19-1999
Re: Gamma Exposure Calculation Needed
I agree with you. I'm a level III, and an engineer, and I would not trust me with a live source. And we have inspectors that couldn't pass 9th grade math but whom you can hand a specimen and can give you the prettiest shots in one or two tries. No argument.

However, the original questions posed are ambiguous.

What formulas do they want? Inverse square laws? half-value layers? disintegration rates? These concepts, except perhaps the latter, are universal in radiography, and are easily found in most texts. Coupled with Isotope data and exposure charts provided by nearly any film supplier, they should be able to extract any information they may need.

Now if they just want to feed thickness measurements of the part into a computer, and a technique chart, including the which film to use, comes rolling off the printer, lots of luck.


: Believe it or not you don't need to be an engineer to be a level II,
: and a GOOD one at that.

: I've met many Level III's that I wouldn't let touch a live source
: let alone expect them to know how to extrapolate a formulae.

: If it's that simple to come up with the formulae why not
: take the minute or two and answer the guys question by giving him
: what he asked for.

: S. Cargill
: asnt Tc1A level II
: RT, PT, MT, UT
: AWS CWI
: PMI Supervisor.


: : For a radiographic Level Three, with his educational
: : background as an engineer, it should be very simple to
: : take the exposure charts, which are distributed by all
: : major film manufacturers, and to extract the mathematic
: : formulas from that charts and to convert them into
: : small PC programs. And, of course, the Level Three has
: : to supply his Level Two's and Level One's with such
: : programs.

: : And, as Trepanier and Ginzel stated, exposure rulers
: : and exposure programs are available. Years ago,
: : exposure rulers were distributed for free by Varian and
: : by Dupont, e.g.

: : And, in addition, if Level Two or Level One candidates
: : are visiting courses of serious NDT education centers,
: : to my knowledge the class mates are exchanging the
: : available programs on their laptops.

: : So, for NDT people which are following the existing NDT
: : education and qualification system, it should be easy
: : to have appropriate exposure programs.

: : NDT beginners should not ask for the programs but
: : should go into the qualification system.

: :
: : Best regards

: : Uli Mletzko

: : NDT Group,
: : State Materials Testing Institute,
: : University of Stuttgart,
: : Germany





    
 
 
Michael Trinidad
Consultant,
LMATS Pty Ltd , Australia, Joined Jan 2003, 138

Michael Trinidad

Consultant,
LMATS Pty Ltd ,
Australia,
Joined Jan 2003
138
03:40 Jul-16-1999
Re: Gamma Exposure Calculation Needed
For Agfa foil packed films D4 and D7 on steel

E = 2.72Yx (X -: 25.4 x 1.1) x 0.108 x (Y -: 25.4)2 -: Z x ff
35


X = thickness (mm)
Y = sfd (mm) Source to film distance
Z = Isotope strength (Ci)
ff = film factor (D4 = 90 D7 = 30)

Note: a. -: is divide (as I can’t find it on my keyboard)
b. the x after 2.72Yx is an indice (wont paste in here correctly). Same goes for the two after (Y -: 25.4)2 "indice"

It is a lot easier using either a slide rule or exposure chart

Kind regards

Michael Trinidad
ETRS NDT Project Supervisor
KBJV Worsley Expansion Project
Direct Tel: 61-8-9781-6232
Fax: 61-8-9781-6233
Email: etrs@kbjv.com




    
 
 
Michael Trinidad
Consultant,
LMATS Pty Ltd , Australia, Joined Jan 2003, 138

Michael Trinidad

Consultant,
LMATS Pty Ltd ,
Australia,
Joined Jan 2003
138
03:45 Jul-16-1999
Re: Gamma Exposure Calculation Needed
it still did not paste very good.....

the Z x ff is supposed to be dived by 35 (ie the 35 was supposed to be underneath)

Apologies

Michael Trinidad




    
 
 

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