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- since 1996 -

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Technical Discussions
Farhang Honarvar
Farhang Honarvar
07:07 Feb-27-2001
Ultrasonic Testing of Spot Welds

Special water-column delay lines are used for NDT of spot welds.
I would like to know on what basis is the length of the delay
line calculated?

Thanks,

-- Farhang.


    
 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
07:52 Feb-27-2001
Re: Ultrasonic Testing of Spot Welds
: Special water-column delay lines are used for NDT of spot welds.
: I would like to know on what basis is the length of the delay
: line calculated?

Generally there are two considerations: convenient mechanical design and manufacturing, and insuring that the transit time through the water path is long enough to permit a number of multiple echoes from the spot weld before the second water path echo occurs. In most applications of this type the exact water path length is not too critical.

--Tom Nelligan


    
 
 
Udo Schlengermann
Consultant, -
Standards Consulting, Germany, Joined Nov 1998, 174

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
174
05:25 Feb-28-2001
Re: Ultrasonic Testing of Spot Welds
Reply by Udo Schlengermann :

By ultrasonic spot weld testing it has to be proven, that the spot weld diameter has a defined size.
There are rules which link the plate thickness to the minimum spot diameter for a correct weld.
An ultrasonic beam has to be chosen which has the same diameter at the position of the weld spot.
Water delay path has to be selected that the beam size on the weld spot has the same size than the minimum acceptable weld spot diameter.

Kind regards
Udo Schlengermann
Krautkramer GmbH & Co OHG, Huerth, Germany
+++++

: Special water-column delay lines are used for NDT of spot welds.
: I would like to know on what basis is the length of the delay
: line calculated?
.
: Thanks,
.
: -- Farhang.
.



    
 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 785

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
785
02:09 Mar-01-2001
Re: Ultrasonic Testing of Spot Welds
: : Special water-column delay lines are used for NDT of spot welds.
: : I would like to know on what basis is the length of the delay
: : line calculated?
.
: Generally there are two considerations: convenient mechanical design and manufacturing, and insuring that the transit time through the water path is long enough to permit a number of multiple echoes from the spot weld before the second water path echo occurs. In most applications of this type the exact water path length is not too critical.
.
: --Tom Nelligan
.
The water path calculation is similar to what is done in immersion testing. The minimum path will be four times the metal thickness plus a little more to take care of the velocity ratios between water and most metals- Swamy


    
 
 
kalantari
kalantari
07:22 Apr-17-2001
Re: Ultrasonic Testing of Spot Welds
: agure of imperfections of spot welds with available methods.
: ultrasonic testing of spot welds.
: the standards about those case.(UT)
: METHOD OF PRACTICAL TEST WITH ULTRASONIC TESTING OF
SPOT WELDS FOR SIMPLE.
:please send each of the which you can.
GOOD LUCK


    
 
 
Jim Knowles
Jim Knowles
00:03 Apr-18-2001
Re: Ultrasonic Testing of Spot Welds
: : agure of imperfections of spot welds with available methods.
: : ultrasonic testing of spot welds.
: : the standards about those case.(UT)
: : METHOD OF PRACTICAL TEST WITH ULTRASONIC TESTING OF
: SPOT WELDS FOR SIMPLE.
: :please send each of the which you can.
: GOOD LUCK
.
Response.
Resistance spot welds tend to be relatively smooth, this enables good acoustic coupling. Therfore contact method using between 10-20MHz compression positined in the centre of the spot weld, multiple repeats should indicate fusion across the weld boundary at the distance of twice the material thickness.
This type of testing has been developed for some time and has a good POD (Probability of Detection)for fusion type flaws.



    
 
 

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