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V.JAGADISH
NDT Inspector
heisco, Kuwait, Joined Aug 2006, 7

V.JAGADISH

NDT Inspector
heisco,
Kuwait,
Joined Aug 2006
7
01:30 Aug-24-2006
back scatter clarification

Correct! A light image of the B means reject. A dark image or no image means accept
According to this answer if there is no image on the radiograph even though i placed a letter B on the back of film then how can i prove the interpretor that i have used a letter B and also I would like to know that is attaching Letter B is mandatory as per ASME SEC V. Kindly clear my doubt.


 
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P V SASTRY
R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D, India, Joined Jan 2003, 195

P V SASTRY

R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D,
India,
Joined Jan 2003
195
01:31 Aug-25-2006
Re: back scatter clarification
Dear Shri Jagadish,

There are two issues to be addressed here.

As far as proving to the inspector that you have put
the 'B' - some amount of trust is imperative. Other
wise how do you prove to the inspector that you have
taken the radiograph of the said weld/component.

The second issue is the statement that if there is a
white'B', reject-no problem.

If there is no 'B', accept- no problem.

But the third part of the statement that If there is a
black'B' accept- This has to be taken with a little
bit of caution and circumspection.

As I mentioned earlier we have paid some extended
attention to the so called case of the black 'B' as
its appearance coincided with poor penetrameter
sensitivity in case of long exposures.

It is always not the case that you get a black 'B'
because of the radiation getting reflected from it. It
is possible, particularly when you are using High
energy radiation as in the case of Co-60, that the
back scattered radiationgets softened while
re-entering through the 'B' and darkens the film more
at that region than the rest. So you get a black 'B'
for the same reason as that of white 'B'.
You have an interesting case to discern the respective
darkening components i.e the reflected versus the back
scattered.

While this may not be true in every situation
protecting your film on the back side is a good idea
when you suspect back scatter.

Best of luck

P V SATRY


----------- Start Original Message -----------
: Correct! A light image of the B means reject. A dark image or no image means accept
: According to this answer if there is no image on the radiograph even though i placed a letter B on the back of film then how can i prove the interpretor that i have used a letter B and also I would like to know that is attaching Letter B is mandatory as per ASME SEC V. Kindly clear my doubt.
------------ End Original Message ------------




 
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