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IMG ULTRASUONI SRL
Ultrasonic transducers for industrial applications (NDT) and medical (Doppler effect). Probes, Ultrasonic instruments, Special systems for NDT.
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Technical Discussions
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
02:27 Sep-30-2013
UT of column to base plate

Why when UT inspecting column flange to base plate weld can I see a signal from backside of the flange. Shouldn't the sound reflect away off the back flange surface and stay in the baseplate instead of returning to transducer.

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
03:09 Sep-30-2013
Re: UT of column to base plate
In Reply to Bill at 02:27 Sep-30-2013 (Opening).

What kind of weld was used?

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
15:05 Sep-30-2013
Re: UT of column to base plate
In Reply to Albert at 03:09 Sep-30-2013 .

Mig "t" joint

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
16:40 Sep-30-2013
Re: UT of column to base plate
In Reply to Bill at 15:05 Sep-30-2013 .

I'm guessing its a fillet weld, is you search the forums, the subject was touched upon.

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
16:54 Sep-30-2013
Re: UT of column to base plate
In Reply to Albert at 16:40 Sep-30-2013 .

No it's not a fillet. The signal is a 1.5" past the weld. It's the backside of baseplate.

    
 
 Reply 
 
Gerald R. Reams
Engineering,
Industry, USA, Joined Aug 2012, 180

Gerald R. Reams

Engineering,
Industry,
USA,
Joined Aug 2012
180
17:50 Sep-30-2013
Re: UT of column to base plate
In Reply to Bill at 16:54 Sep-30-2013 .

What are all the parameters of the examination?

Joint Design
Material Thicknesses
Tranducers
Wedges
etc.

One could only guess without sufficient information.

Gerald

    
 
 Reply 
 
andrew cunningham
NDT Inspector
Canada, Joined Jun 2008, 238

andrew cunningham

NDT Inspector
Canada,
Joined Jun 2008
238
19:45 Sep-30-2013
Re: UT of column to base plate
In Reply to Bill at 02:27 Sep-30-2013 (Opening).

If it is a full pen weld, the sound should go through into the baseplate without reflecting any sound back to the transducer. If you have found a reflector that is not acceptable to code, you should call it out for repair. The reason we test welds is to find the anomalies the welder leaves behind.
There are some pre-welded T joints coming in from different parts of the world, that I have found to be fillet welds. It appears that they thought galvanizing would hide fillet. (They were wrong.)

All the best

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
20:09 Sep-30-2013
Re: UT of column to base plate
In Reply to andrew cunningham at 19:45 Sep-30-2013 .

There's not an indication in the weld but the back of the baseplate is producing a signal. Or even better why does a free edge produce a signal and I don't mean the corner but the edge of a plate? Shouldn't the sound hit the edge and reflect away from the transducer. ie fillet welded t joint needs tandem probes to detect

    
 
 Reply 
 
Gerald R. Reams
Engineering,
Industry, USA, Joined Aug 2012, 180

Gerald R. Reams

Engineering,
Industry,
USA,
Joined Aug 2012
180
20:38 Sep-30-2013
Re: UT of column to base plate
In Reply to Bill at 20:09 Sep-30-2013 .

Lamination in the plate could provide such a reflection.

Regards,
Gerald

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
01:55 Oct-01-2013
Re: UT of column to base plate
In Reply to Bill at 20:09 Sep-30-2013 .

Bill,

If you can draw a side profile of the plate to scale on a sheet of paper and with a protractor try to draw out the beam path, that might help with visualizing how its possible for the sound to be reflected back to your transducer.

You can resolve the possible lamination issue with a longitudinal surface inspection.

and are you asking why there is a reflection at a free boundary (metal/air interface)?

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
02:44 Oct-01-2013
Re: UT of column to base plate
In Reply to Albert at 01:55 Oct-01-2013 .

Yes A free boundary that is perpendicular to sound beam, like the edge of a plate. I know why it reflects from a free boundary but why does the sound reflect back to the transducer from a free edge ie. plate edge or from the back of a base plate

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
03:18 Oct-01-2013
Re: UT of column to base plate
zoom image
I've attached a hastily made sketch,



Well if the beam is perpendicular (normal) then you can expect a reflection similar to what you would encounter while doing a longitudinal inspection, less amplitude considering the longer bean travel.



My interest in asking about the free boundary, is that it would make a difference in the amount of energy reflected. There is a diagram in the UT section that explains how the reflection / transmission coefficients affect the amount of energy received from a back wall reflection in an immersed piece of steel.
    
 
 Reply 
 
Bill
Bill
03:33 Oct-01-2013
Re: UT of column to base plate
In Reply to Albert at 03:18 Oct-01-2013 .

In your sketch the sound reflects off the edge of plate and doesn't reflect back in the same path it came but rather down in the 5th leg off the free edge and eventually ends up back to the transducer. So if the transducer was positioned close enough to the free edge that the sound hits the edge in the first leg then the sound would bypass returning to the transducer?

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
03:57 Oct-01-2013
Re: UT of column to base plate
In Reply to Bill at 03:33 Oct-01-2013 .

zoom image
Bill,

It's all angles, I think it's called a corner trap,

I have attached another picture, it that what you mean?

You can try to decrease the range on the instrument to only capture the area of interest, avoiding the signal that isn't of interest.

    
 
 Reply 
 
gaurav chopra
gaurav chopra
11:22 Oct-01-2013
Re: UT of column to base plate
In Reply to Albert at 03:57 Oct-01-2013 .

zoom image
I have uploaded an image of a base column where the I beam is welded to the base plate.
the base column is fabricated in the refinery area which will be used as a pipe rack. The dimensions may vary but i have put it up on what i have done the manual UT practically.

In this case, the weld is a single V double bevel where the material is carbon steel and arc welding or MIG welding is used as per the thickness.

i also had the same question in my mind when i used to scan the weld from the top side there used to be a significant indication coming out in the screen.

When i saw the skip distance accordingly with the beam path in consideration, it was far out from the base plate, but it wont actually be, and when i made the drawing, there were internal reflections. and the probe is mostly nearer to the weld(higher probe angles mostly considered for such reflections)

As shown in the drawing, grooves are made in the web area so as to provide access to the welder to weld the metal as per the welding angle. the groove was made by cutting it by either gas cutter or by grinding and the results of it was sharp reflector edges.

When i used to plot my sound path, it used to come from that groove area only.
I am still not sure if practically its right or no, so i have made the drawing for your references so you all can refer and find me a solution for this

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
13:56 Oct-01-2013
Re: UT of column to base plate
In Reply to gaurav chopra at 11:22 Oct-01-2013 .

The pic you are showing is the exact joint configuration I'm talking about. Why do you receive a signal back from the back of the baseplate, there isn't a corner to trap the sound and return.

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
14:55 Oct-01-2013
Re: UT of column to base plate
In Reply to Bill at 13:56 Oct-01-2013 .

Bill,

If its a full penetration weld, and the instrument range is set long enough, you can expect to see the back wall of the plate, the possibility of laminations previously mentioned can become laminar tearing in the base plate due to the welding heat input, after cooling causing the tear. you can also expect some "noise" from the HAZ and the weld its self due to the variations in grain structure(base metal being worked, refining the grain structure, and a weld being basically cast metal).

Just out of curiosity, if you have a procedure you are working with, does it address any of the issues you are encountering?

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
15:52 Oct-01-2013
Re: UT of column to base plate
In Reply to Albert at 14:55 Oct-01-2013 .

Why do you see the back of the baseplate? Shouldn't the sound reflect away from the transducer not back in the same path it came?

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
16:58 Oct-01-2013
Re: UT of column to base plate
In Reply to Bill at 15:52 Oct-01-2013 .

Your right, for some reason I was still thinking the end of the plate.

do a Google image search for laminar tearing, you should find some good info..

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
18:12 Oct-01-2013
Re: UT of column to base plate
In Reply to Albert at 16:58 Oct-01-2013 .

Does some portion of the sound reflect back the same path it came off the back of the baseplate?

    
 
 Reply 
 
P V SASTRY
R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D, India, Joined Jan 2003, 195

P V SASTRY

R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D,
India,
Joined Jan 2003
195
22:11 Oct-01-2013
Re: UT of column to base plate
In Reply to Bill at 18:12 Oct-01-2013 .


Dear Friend,

I am following this discussion. At this stage I feel you should give the A-scan representations of the reflection that you are getting (two or more screens with slightly different positions) and a dimensional sketch showing the probe position for each screen.

Then your specific question of how the signal is coming from the back plate or from somewhere else can be answered more precisely by the many experts on this forum including those who have responded.

Best wishes

P V SASTRY

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
23:27 Oct-01-2013
Re: UT of column to base plate
In Reply to P V SASTRY at 22:11 Oct-01-2013 .

My only question is does some of the sound when it hits a vertical reflective surface reflect back the same path it came?

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
00:52 Oct-02-2013
Re: UT of column to base plate
In Reply to Bill at 23:27 Oct-01-2013 .

http://www.youtube.com/user/MODELULTS

Check out the link above, its UT wave propagation simulations.

Anything is possible, but normally I'd say no.

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
01:41 Oct-02-2013
Re: UT of column to base plate
In Reply to Albert at 00:52 Oct-02-2013 .

I just tried a 70 degree probe on the free edge of a 3" thick calibration block and if I put the exit point of the transducer near the edge I can see the edge of the plate in the 1st leg not just the corner but the edge of the plate.

    
 
 Reply 
 
Albert
Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation, USA, Joined Jun 2012, 140

Albert

Other, ASNT NDT Level III (MT, PT, UT and ET )
Aviation,
USA,
Joined Jun 2012
140
03:15 Oct-02-2013
Re: UT of column to base plate
In Reply to Bill at 01:41 Oct-02-2013 .

Bill,

Earlier in the day I emailed you some UT weld inspection/ metalurgy specific reading material.

We can't seem to clear this up for you, maybe at your work place you have access to a senior UT tech or a level III that might be more well versed in your exact application.

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
15:38 Oct-02-2013
Re: UT of column to base plate
In Reply to Albert at 03:15 Oct-02-2013 .

Does anybody know why I can see the edge of the calibration block in the first leg with a 70 degree transducer?

    
 
 Reply 
 
Charlie Jackson
Charlie Jackson
16:42 Oct-02-2013
Re: UT of column to base plate
In Reply to Bill at 15:38 Oct-02-2013 .

Bill

Remember that whilst we plot with a single line the centre of the beam and imagine all the energy reflected away from the probe this is not a true reflection(pun) of what actually happens. You need to consider beam spread and low amplitude reflections of the far side surface undulations when using single skip or 1/2 leg.
Its used as confirmation when testing tee butts and TKY joints that the sound is passing through theb wall and material unimpeded by material or weld defects.
The fact you are getting a good echo from the far side at 1/2 leg suggests you are using the correct levels of gain to ensure detection of relevant flaws.
Cheers Charlie

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
18:37 Oct-02-2013
Re: UT of column to base plate
In Reply to Charlie Jackson at 16:42 Oct-02-2013 .

Charlie,

So your saying that this reflection signal observed from the back of the baseplate and the free edge of the calibration block is some of the sound is reflecting back the same path it came? So the fungal I am seeing is expected?

    
 
 Reply 
 
P V SASTRY
R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D, India, Joined Jan 2003, 195

P V SASTRY

R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D,
India,
Joined Jan 2003
195
22:00 Oct-02-2013
Re: UT of column to base plate
In Reply to Bill at 23:27 Oct-01-2013 .


Dear Friend,

It is good that you have so many questions but to give a proper answer, some inputs are required. I asked for some inputs and in reply you asked one more question. That is OK

You have asked"My only question is does some of the sound when it hits a vertical reflective surface reflect back the same path it came?"

Now may I ask you is it from a normal probe or from angle probe. The answer should be obvious to you.

Now you may say that all along the context is always shear wave probes only. Then the answer is no under normal conditions. ( i.e. if they are man made surfaces like rolled or machined etc)

Best wishes

P V SASTRY


    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
22:36 Oct-02-2013
Re: UT of column to base plate
In Reply to P V SASTRY at 22:00 Oct-02-2013 .

Angle probe! Some of the sound must reflect back the same path it came or you wouldn't be able to see a signal from a free edge. Try a 70 degree probe on the edge of a calibration block and you will see a signal from the edge.

    
 
 Reply 
 
gaurav chopra
gaurav chopra
07:00 Oct-03-2013
Re: UT of column to base plate
In Reply to Bill at 22:36 Oct-02-2013 .

Bill,
i forgot to mention one thing to all of you. if you perform the test and observe carefully, the reflection which is coming beyond the base plate is only in the area if we scan in between centre of flange.

the centre of the flange where it is joined with the web and there is an access made which is the actual cause of reflection excluding any abnormality in the base plate.

Bill, carry out few more inspections, observe the centre area of the flange, note down the readings and take the exact dimensions of every thing and plot it. you will get the point of your interest.

    
 
 Reply 
 
Charlie Jackson
Charlie Jackson
07:48 Oct-03-2013
Re: UT of column to base plate
In Reply to Bill at 18:37 Oct-02-2013 .

Bill

It is expected and as Ive explained you can use it to confirm other aspects of your inspection.
Its like using a 45 at 1/2 leg you will see the far side 'rumble' which gives you information about the surface roughness, in effect the 70 response you are seeing is hitting the wall at 20degrees so you would expect a good response. This response will be higher if you are using a 2 MHz (popular on your side of the pond) probe because of the increase in beam spread.

Dont forget a lot of voices out there try to make it a difficult science but it just follows simple rules - happy probing
Charlie

    
 
 Reply 
 
Bill
NDT Inspector
USA, Joined Oct 2009, 49

Bill

NDT Inspector
USA,
Joined Oct 2009
49
18:54 Oct-03-2013
Re: UT of column to base plate
In Reply to Charlie Jackson at 07:48 Oct-03-2013 .

Would you expect to see a better reflection off the free edge with a 70 or a 45?

    
 
 Reply 
 
George Shields
NDT Inspector, NDT Level 3
United Kingdom, Joined Oct 2012, 30

George Shields

NDT Inspector, NDT Level 3
United Kingdom,
Joined Oct 2012
30
05:59 Oct-04-2013
Re: UT of column to base plate
In Reply to Bill at 18:54 Oct-03-2013 .

You would in most cases get a stronger signal with a 70. Due to this being closer to being perpendicular to the base plate than the 45 would.

    
 
 Reply 
 
George Shields
NDT Inspector, NDT Level 3
United Kingdom, Joined Oct 2012, 30

George Shields

NDT Inspector, NDT Level 3
United Kingdom,
Joined Oct 2012
30
05:59 Oct-04-2013
Re: UT of column to base plate
In Reply to Bill at 18:54 Oct-03-2013 .

You would in most cases get a stronger signal with a 70. Due to this being closer to being perpendicular to the base plate than the 45 would.

    
 
 Reply 
 

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