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ACS-Solutions GmbH
develop and manufacture hi-tech devices for Ultrasonic Testing

883 views
02:03 Nov-23-1999
António Pereira de Sousa
Dissimilar Welds

On 460 welds, between SA213T99 and SA213T22(tubes with 0.5x5mm) has been made a magnetic particle testing.
They were detected 50% of welds with longitudinal linear indications on side TA213T91.
After retesting, by Penetrant testing, only 10% of them have shown indications from cracks.
Why?



 
03:46 Nov-24-1999

Michael Trinidad

Consultant, API 510 570 & 653
Marine Inspection Service Pty Ltd (MIS),
Australia,
Joined Jan 2003
138
Re: Dissimilar Welds This would most likely be the indications from the magnetic leakage field occuring around the large change in permeability between the two disimilar metals. It has often caught out technicians, we had a similar case in the fourm only a few months back.

Kindest Regards

Michael Trinidad


 
01:57 Nov-24-1999
D. Scott Sullivan
Re: Dissimilar Welds
: This would most likely be the indications from the magnetic leakage field occuring around the large change in permeability between the two disimilar metals. It has often caught out technicians, we had a similar case in the fourm only a few months back.

: Kindest Regards

: Michael Trinidad

: Mr. Trinidad's opinion is most likely correct. Another possibility could be that you were picking up indications of sub-surface lack of fusion with the magnetic particle method. If the lack of fusion was subsurface, the penetrant method would not detect it.
If you cut a cross section and etch the weld, you could confirm this. If you can not cut the weld, a X-ray of the suspect area should be able to readily detect lack of fusion.

:D. Scott Sullivan
Sr. NDT Engineer
RT, ET, MT & PT Level III


 
07:56 Nov-24-1999
Ken Head
Re: Dissimilar Welds :
: : This would most likely be the indications from the magnetic leakage field occuring around the large change in permeability between the two disimilar metals. It has often caught out technicians, we had a similar case in the fourm only a few months back.

: : Kindest Regards

: : Michael Trinidad

: : Mr. Trinidad's opinion is most likely correct. Another possibility could be that you were picking up indications of sub-surface lack of fusion with the magnetic particle method. If the lack of fusion was subsurface, the penetrant method would not detect it.
: If you cut a cross section and etch the weld, you could confirm this. If you can not cut the weld, a X-ray of the suspect area should be able to readily detect lack of fusion.

I think you are mistaken on using X-Ray to determine the presence (or
lack there of) of fusion. As a rule, radiography is not the perferred
method for detecting "non-fusion". the method most suited for this task
is UT.
Ken Head
Sr. Level III
: :D. Scott Sullivan
: Sr. NDT Engineer
: RT, ET, MT & PT Level III




 
06:03 Nov-29-1999
D. Scott Sullivan
Re: Dissimilar Welds Ken,

I don't believe I am mistaken regarding the detection of sidewall lack-of-fussion (LOF).

X-ray would be the preffered method. Although you can detect LOF with the ultrasonic method, LOF, weld root cracks and lack-of-penetration (LOP) all give essentially the same type of ultrasonic signal. The reflected signals are narrow and appear at the same location. These signals can in some cases be differentiated by determining the extent of the flaw in the transverse direction. This is not always possible.

In any case, as far as a back-up inspection to MT, I agree that RT or UT could quickly confirm wether or not the MT indication was relevant.

Best Regards,

D. Scott Sullivan



 


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