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Technical Discussions
Oussema
Oussema
18:37 Mar-16-2016
Defect
zoom image



Help me it is concavity or luck penetration

1
 
 Reply 
 
jon wallis
NDT Inspector, -
Netherlands, Joined Feb 2010, 626

jon wallis

NDT Inspector, -
Netherlands,
Joined Feb 2010
626
07:37 Mar-17-2016
Re: Defect
In Reply to Oussema at 18:37 Mar-16-2016 (Opening).

This is root concavity.
Judging from the photograph, it seems to be not too serious, you can see at the left side of the image the shape and depth of the discontinuity. Even if this is acceptable to whichever code you are working to, go to the welders foreman and tell him (her), this is a welders mistake.

 
 Reply 
 
N B Rengaraju
NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA., India, Joined Sep 2014, 106

N B Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
106
09:16 Mar-17-2016
Re: Defect
In Reply to Oussema at 18:37 Mar-16-2016 (Opening).

Dear Friend,

The indication even does not look like a concavity. For Root concavity, you need the optical density on the concave area to be more than the adjacent parent metal area, which is not the case here, as seen.

At the most, it can be termed as a Minor underfill or surface depression due to which the internal protrusion is not even.

 
 Reply 
 
jon wallis
NDT Inspector, -
Netherlands, Joined Feb 2010, 626

jon wallis

NDT Inspector, -
Netherlands,
Joined Feb 2010
626
11:53 Mar-17-2016
Re: Defect
In Reply to N B Rengaraju at 09:16 Mar-17-2016 .

I disagree, if you look at the full size picture you'll see suck -back of the root at the side quite clearly. I do agree that it is not severe and would probably be acceptable to code or norm but it is still a concave root both in a linguistic and radiographic sense.

 
 Reply 
 
N B Rengaraju
NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA., India, Joined Sep 2014, 106

N B Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
106
12:23 Mar-17-2016
Re: Defect
In Reply to jon wallis at 11:53 Mar-17-2016 .

Yes...call it a suck back. The indication does not fall under which internal concavity is defined.

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1286

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1286
13:34 Mar-17-2016
Re: Defect
In Reply to jon wallis at 11:53 Mar-17-2016 .

I concur with Jon. In pipeliner parlance, the pass made over the root pass is called the "Hot Pass" and one of its side -effects is to reduce some of the excess penetration in the root pass. The comment by Rengaraju that the optical density must be more than the parent material is not applicable in that you cannot make this comparison when there is significant external reinforcement.
On the NDT-ed.org website we read: Internal concavity or suck back is a condition where the weld metal has contracted as it cools and has been drawn up into the root of the weld. On a radiograph it looks similar to a lack of penetration but the line has irregular edges and it is often quite wide in the center of the weld image.

 
 Reply 
 
N.B. Rengaraju
NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA., India, Joined Sep 2014, 106

N.B. Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
106
14:06 Mar-17-2016
Re: Defect
In Reply to Ed Ginzel at 13:34 Mar-17-2016 .

Density comparison done for internal concavity shall be with respect to allowable weld reinforcement allowed as per the code. The radiograph shown does not reveal any significant excessive external reinforcement.

 
 Reply 
 
jon wallis
NDT Inspector, -
Netherlands, Joined Feb 2010, 626

jon wallis

NDT Inspector, -
Netherlands,
Joined Feb 2010
626
15:34 Mar-17-2016
Re: Defect
In Reply to N.B. Rengaraju at 14:06 Mar-17-2016 .

Ed talks about significant external reinforcement and this has nothing to do with excessive external reinforcement.
If you compare density of the through thickness at the weld with that of the parent metal, this will always include the external reinforcement and as this is a variable it will not be an accurate measurement. This is done in practice as a 'there is no other way of measuring' method. Euronorms ask you to measure the height of any concavity which, of course, in many cases is impossible. But coming back to Mr Rengaraju's point, that concavity is only concavity when it is unacceptable according to norm, this is not correct as I previously mentioned, concave is a physical state whether it is slight or heavy.

 
 Reply 
 
N.B. Rengaraju
NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA., India, Joined Sep 2014, 106

N.B. Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
106
16:01 Mar-17-2016
Re: Defect
In Reply to jon wallis at 15:34 Mar-17-2016 .

I was also speaking about the same...significant extenal reinforcement. Only the word - excessive - was used in addition. And I never said that concavity is a concavity only when its unacceptable. Concavity as defined by me has its own acceptance standards in codes apart from the primary requirement of density variation. A minor suck back or underfill cannot be called a internal concavity.

 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
02:21 Mar-18-2016
Re: Defect
In Reply to Oussema at 18:37 Mar-16-2016 (Opening).

zoom image



Digital processing complete.
 
 Reply 
 
Manfred Richter
Consultant,
Richter & Tomasi Ltd., Brazil, Joined Jan 2008, 31

Manfred Richter

Consultant,
Richter & Tomasi Ltd.,
Brazil,
Joined Jan 2008
31
13:51 Mar-21-2016
Re: Defect
In Reply to Volodymyr at 02:21 Mar-18-2016 .

I agree with Jon and Ed, the indication is wide and at the digital image provided by Mr. Volodymyr in the left whte thickness profile it can be seen clerly the round profile of concavity.

1
 
 Reply 
 
N B Rengaraju
NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA., India, Joined Sep 2014, 106

N B Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
106
02:24 Mar-22-2016
Re: Defect
In Reply to Manfred Richter at 13:51 Mar-21-2016 .

The image as seen after Digital Processing is an electronically enhanced image. Most of the Interpreters have to interpret and evaluate based on Actual Radiographs, not on processed images. Even here, it represents more a suck back.

1
 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
15:02 Mar-22-2016
Re: Defect
In Reply to N B Rengaraju at 02:24 Mar-22-2016 .

I totally agree with Mr. Rengaraju. I resorted to this method in difficult cases , but didn't open a secret :)
Is that here in the debate. It's like you put on good glasses.

 
 Reply 
 
Leo
NDT Inspector,
Norway, Joined May 2008, 104

Leo

NDT Inspector,
Norway,
Joined May 2008
104
17:13 Mar-22-2016
Re: Defect
In Reply to N B Rengaraju at 02:24 Mar-22-2016 .

English ain't my first language, but always thought that *suck back* is a slang for *root concavity*. Anyway in my practice that sort of indication was always called Root concavity.

1
 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1286

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1286
17:44 Mar-22-2016
Re: Defect
In Reply to Leo at 17:13 Mar-22-2016 .

Leo, er du riktig , og dette er enig med definisjonen sett i ndt-ed.org

 
 Reply 
 

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