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1077 views
00:35 Oct-12-2005
Kaveh Edalati
Criteria for selecting the DWSI or DWDI or Elliptical techniques in in-service pipes

Dear friends
Thank you for your comments on IQI selection in double wall radiography of pipes.
Now, I have two problems:
1- What are the criteria for selecting the radiography technique in double wall radiography of pipes?
In some standards such as ASTM and ASME, when pipe diameter is up to 89 mm, double wall and double image radiography technique shall be used.
But we can not see the clear criterion for selecting the elliptical technique in ASTM or ASME. In API if pipe diameter is up to 63 mm, elliptical should be used.

2- Another problem is maximum allowable source to film distance (SFD) in double wall single image radiography. For example, when minimum SFD is 120 and pipe diameter is 95 mm, what is the practical SFD?
Or, when minimum SFD is 140 and pipe diameter is 95 mm, what is the practical SFD? I think that if SFD is set to 140, the image of upper wall cause in decreasing image quality.
I look forward your comments.

Thank you,
Kaveh


 
05:36 Nov-02-2005
Payam
Re: Criteria for selecting the DWSI or DWDI or Elliptical techniques in in-service pipes ----------- Start Original Message -----------
: Dear friends
: Thank you for your comments on IQI selection in double wall radiography of pipes.
: Now, I have two problems:
: 1- What are the criteria for selecting the radiography technique in double wall radiography of pipes?
: In some standards such as ASTM and ASME, when pipe diameter is up to 89 mm, double wall and double image radiography technique shall be used.
: But we can not see the clear criterion for selecting the elliptical technique in ASTM or ASME. In API if pipe diameter is up to 63 mm, elliptical should be used.
: 2- Another problem is maximum allowable source to film distance (SFD) in double wall single image radiography. For example, when minimum SFD is 120 and pipe diameter is 95 mm, what is the practical SFD?
: Or, when minimum SFD is 140 and pipe diameter is 95 mm, what is the practical SFD? I think that if SFD is set to 140, the image of upper wall cause in decreasing image quality.
: I look forward your comments.
: Thank you,
: Kaveh
------------ End Original Message ------------

Hi Kaveh
As you wrote, there are some chalenge in this case. But you are free in many cases for technique selection in radiography according to your experience.
Payam



 
08:47 Nov-26-2006
Houston
Layne 5e6a9d3147aa


 


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