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- since 1996 -

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Technical Discussions
Nick Welland
Nick Welland
01:48 Mar-02-2004
RT Contact or Elliptical

Is it PERMISSIBLE (rather than USUAL) to use DWS technique instead of DWD (elliptical) on 2" pipe butts under ASME V Art 2?
Regards
Nick


    
 
 
Dent McIntyre
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 248

Dent McIntyre

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
248
04:15 Mar-02-2004
Re: RT Contact or Elliptical
----------- Start Original Message -----------
: Is it PERMISSIBLE (rather than USUAL) to use DWS technique instead of DWD (elliptical) on 2" pipe butts under ASME V Art 2?
: Regards
: Nick
------------ End Original Message ------------

See Par T-271. It says whenever practical a single wall exposure technique 'shall' be used.

Other than this 'requirement' because the word 'may' is uded, you have you choice of double or single wall viewing.



    
 
 
Ed Trotter
Ed Trotter
08:40 Mar-02-2004
Re: RT Contact or Elliptical
----------- Start Original Message -----------
: : Is it PERMISSIBLE (rather than USUAL) to use DWS technique instead of DWD (elliptical) on 2" pipe butts under ASME V Art 2?
: : Regards
: : Nick
: See Par T-271. It says whenever practical a single wall exposure technique 'shall' be used.
: Other than this 'requirement' because the word 'may' is uded, you have you choice of double or single wall viewing.
------------ End Original Message ------------

As long as you can meet your geometric unsharpness requirements.


    
 
 
steve hornby
steve hornby
01:28 Mar-03-2004
Re: RT Contact or Elliptical
It is possible to use DWSI on pipework less than 100mm diameter, however it should be born in mind that at least 6 major root defects then become less detectable, or in some cases impossible to asses using the DWSI technique. These are:- excessive root protrusion, excessive root concavity, angularity, misalignment, sidewall fusion,tunsten on the root. Also usually a minimum of four exposures would be required as opposed to the usual three neccessary for DWDI up to 100mm outside diameter.Much can be gained using the sidewall information of the DWDI technique
----------- Start Original Message -----------
: : : Is it PERMISSIBLE (rather than USUAL) to use DWS technique instead of DWD (elliptical) on 2" pipe butts under ASME V Art 2?
: : : Regards
: : : Nick
: : See Par T-271. It says whenever practical a single wall exposure technique 'shall' be used.
: : Other than this 'requirement' because the word 'may' is uded, you have you choice of double or single wall viewing.
: As long as you can meet your geometric unsharpness requirements.
------------ End Original Message ------------




    
 
 
General
General
07:09 Mar-06-2004
Re: RT Contact or Elliptical
You can do contact on piping down to 2" and even 1.5" depending on the wall thickness. As long as you are meeting the geometric unsharpness requirements you are accptable to code. Most people dont do contact on small bore piping anymore but it is perfectly accceptable and I personally think that it works fine. You can do it in three shots as well. Just have to watch the densitys at the ends of the film so they dont vary by more than 0.5. The one thing you do have to watch is if you get in large sources in the 120 ci. range that the source diagonal dimension is oing to be larger than a new source at say 60 ci. so this is going to increase your unsharpness.

----------- Start Original Message -----------
: It is possible to use DWSI on pipework less than 100mm diameter, however it should be born in mind that at least 6 major root defects then become less detectable, or in some cases impossible to asses using the DWSI technique. These are:- excessive root protrusion, excessive root concavity, angularity, misalignment, sidewall fusion,tunsten on the root. Also usually a minimum of four exposures would be required as opposed to the usual three neccessary for DWDI up to 100mm outside diameter.Much can be gained using the sidewall information of the DWDI technique
: : : : Is it PERMISSIBLE (rather than USUAL) to use DWS technique instead of DWD (elliptical) on 2" pipe butts under ASME V Art 2?
: : : : Regards
: : : : Nick
: : : See Par T-271. It says whenever practical a single wall exposure technique 'shall' be used.
: : : Other than this 'requirement' because the word 'may' is uded, you have you choice of double or single wall viewing.
: : As long as you can meet your geometric unsharpness requirements.
------------ End Original Message ------------




    
 
 
Steven Johnson
Consultant
USA, Joined Mar 2004, 16

Steven Johnson

Consultant
USA,
Joined Mar 2004
16
00:42 Mar-13-2004
Re: RT Contact or Elliptical
You can order sources with smaller focal spot sizes, all that means instead of getting 10 waffers which produced 100 curies, you will end up with 4 waffers and 40 curies. Check to make sure your source supplier spring loads the waffers to keep them buddled up.
We used this technique a lot to cut down exposure time & dose and shooting contact.


    
 
 

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