Re: NDT Methods (TOFD) for Flaw Detection during Welding

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Re: NDT Methods (TOFD) for Flaw Detection during Welding
Posted by: Shaun Lawson , E-mail: s.lawson@surrey.ac.uk, on February 19, 1998 at 19:15:28:
In Reply to: NDT Methods (TOFD) for Flaw Detection during Welding posted by : Rolf Diederichs on February 16, 1998 at 11:00:48:
>>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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Detectability of different defect types using TOFD

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Re: NDT Methods (TOFD) for Flaw Detection during Welding Hassan Rahimi 08:34 6/10/2000 (0)

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: >>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 : ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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