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Technical Discussions
Rolf Diederichs
Director,
NDT.net, Germany, Joined Nov 1998, 605

Rolf Diederichs

Director,
NDT.net,
Germany,
Joined Nov 1998
605
01:00 Feb-16-1998
NDT Methods (TOFD) for Flaw Detection during Welding

This issue is addressed to Dr. Shaun Lawson who provided this
News topic on NDTnet 02/98.

It is written [1] :
'Defects were deliberately implanted into the testpieces by Nordon welders
at various stages of weld completion'

I wonder what types and sizes of inclusions were implanted for this trials.

From our former TOFD themes on NDTnet we know about certain POD problems
with the TOFD method.

I would appreciate if Dr. Lawson could provide more detailed information.

Rolf Diederichs


[1] http://www.ndt.net/news/1998/surrey/surrey.htm
NDT Methods for Flaw Detection during Welding.
The final ultrasonic TOFD trials of the BRITE-EURAM II project 'NDT Methods for Flaw Detection During Welding' took place in Oct 1997. The aim of the trials was to demonstrate NDT using TOFD whilst welding was taking place - i.e. the ultrasonic probes were to be placed a short distance behind the weld torch. The trials successfully demonstrated the techniques and methods developed during the four year study to undertake NDT during welding.
.......
'The trials successfully demonstrated the techniques and methods developed during the four year study to undertake NDT during welding. A number of welded test plates were prepared - one set of TIG welded 25mm thick steel, the other submerged arc welded 80 mm thick steel. Defects were deliberately implanted into the testpieces by Nordon welders at various stages of weld completion - Figure 2 shows an example of this work in progress. These defects included tungsten inclusions (for TIG welds), root cracks, porosities, lack of fusion, slag inclusions (for SA welds) and lack of penetration. The techniques that are required in order to implant suitably representative defects into the welds were developed by Nordon at an early stage in the project.'



    
 
 
Shaun Lawson
Shaun Lawson
09:15 Feb-19-1998
Re: NDT Methods (TOFD) for Flaw Detection during Welding
>>It is written [1] :
>>'Defects were deliberately implanted into the testpieces by Nordon welders
>>at various stages of weld completion'
>>
>>I wonder what types and sizes of inclusions were implanted for this trials.

Both TIG and SAW welding testpieces were manufactured . All deliberately
implanted defects were between 15mm and 30 mm in length - their
volumetric size varied with their type. Note though it is very difficult to
produce a 'defect' of exact requirements !

I have summarised defect types and their detectability in the article :-
http://www.ndt.net/article/0298/forum/defects.htm

The thinner TIG plates caused most problems - though Tungsten inclusions
were hard to detect at all completions. At very thin completions the
automated software had difficulty resolving the diffference between the
lateral/backwall waves and the defects - though these were often
discernable by manual means.

>>From our former TOFD themes on NDTnet we know about certain POD problems
>>with the TOFD method.

Note that the real aim of the trials was to determine whether defects
could be detected at high temps, during welding and at incomplete weld
completions rather than to demonstrate POD for any particular defect type.


Shaun.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Shaun Lawson (tel: 01483 259681)
Mechatronic Systems & Robotics Research Group
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




    
 
 
Hassan Rahimi
Hassan Rahimi
08:34 Jun-10-2000
Re: NDT Methods (TOFD) for Flaw Detection during Welding
: >>It is written [1] :
: >>'Defects were deliberately implanted into the testpieces by Nordon welders
: >>at various stages of weld completion'
: >>
: >>I wonder what types and sizes of inclusions were implanted for this trials.

: Both TIG and SAW welding testpieces were manufactured . All deliberately
: implanted defects were between 15mm and 30 mm in length - their
: volumetric size varied with their type. Note though it is very difficult to
: produce a 'defect' of exact requirements !

: I have summarised defect types and their detectability in the article :-
: http://www.ndt.net/article/0298/forum/defects.htm

: The thinner TIG plates caused most problems - though Tungsten inclusions
: were hard to detect at all completions. At very thin completions the
: automated software had difficulty resolving the diffference between the
: lateral/backwall waves and the defects - though these were often
: discernable by manual means.

: >>From our former TOFD themes onNDTnet we know about certain POD problems
: >>with the TOFD method.

: Note that the real aim of the trials was to determine whether defects
: could be detected at high temps, during welding and at incomplete weld
: completions rather than to demonstrate POD for any particular defect type.

:
: Shaun.
: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
: Dr. Shaun Lawson (tel: 01483 259681)
: Mechatronic Systems & Robotics Research Group
: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




    
 
 
rejumohan
rejumohan
05:56 Dec-02-2002
Re: NDT Methods (TOFD) for Flaw Detection during Welding
: This issue is addressed to Dr. Shaun Lawson who provided this
: News topic on NDTnet 02/98.

: It is written [1] :
: 'Defects were deliberately implanted into the testpieces by Nordon welders
: at various stages of weld completion'

: I wonder what types and sizes of inclusions were implanted for this trials.
sir,
please send me some details of ndt.i am afinal year student in engineering studying in india.ihave to submit aseminar on ndt welding.please do the needful
: From our former TOFD themes on NDTnet we know about certain POD problems
: with the TOFD method.

: I would appreciate if Dr. Lawson could provide more detailed information.

: Rolf Diederichs

:
: [1] http://www.ndt.net/news/1998/surrey/surrey.htm
: NDT Methods for Flaw Detection during Welding.
: The final ultrasonic TOFD trials of the BRITE-EURAM II project 'NDT Methods for Flaw Detection During Welding' took place in Oct 1997. The aim of the trials was to demonstrate NDT using TOFD whilst welding was taking place - i.e. the ultrasonic probes were to be placed a short distance behind the weld torch. The trials successfully demonstrated the techniques and methods developed during the four year study to undertake NDT during welding.
: .......
: 'The trials successfully demonstrated the techniques and methods developed during the four year study to undertake NDT during welding. A number of welded test plates were prepared - one set of TIG welded 25mm thick steel, the other submerged arc welded 80 mm thick steel. Defects were deliberately implanted into the testpieces by Nordon welders at various stages of weld completion - Figure 2 shows an example of this work in progress. These defects included tungsten inclusions (for TIG welds), root cracks, porosities, lack of fusion, slag inclusions (for SA welds) and lack of penetration. The techniques that are required in order to implant suitably representative defects into the welds were developed by Nordon at an early stage in the project.'
:




    
 
 

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