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Acoustic Emission Consulting, Inc.
Acoustic Emission Consulting, Inc. specializes in the design of small portable AE instruments for field and lab use.
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Technical Discussions
Naser
Iran, Joined Nov 2018, 4

Naser

Iran,
Joined Nov 2018
4
20:25 Nov-25-2019
Phased Array vs RT

Hi everybody
In a project, we inspected some of the welds (base metal thickness=6 mm) with PAUT (Brand=Veo) technique. then we decided to recheck the PAUT results with radiography. The few discontinuities that were accepted by PAUT were completely rejected with radiography. Now, share with us if you have same experience?
Tell me about the reason of results duality ?
As I know, the 6 mm thickness is the threshold of ultrasound technique. Is it possible that the continuous defects were seen discontinuously in 6 mm?

 
 Reply 
 
Matthias Dreifeld
NDT Inspector, CEO
Dreifeld Materialprüftechnik, Germany, Joined Sep 2005, 100

Matthias Dreifeld

NDT Inspector, CEO
Dreifeld Materialprüftechnik,
Germany,
Joined Sep 2005
100
10:53 Nov-26-2019
Re: Phased Array vs RT
In Reply to Naser at 20:25 Nov-25-2019 (Opening).

That is because those two methods have a completely different way to collect data and analyze them.

Think about it, in UTPA you evaluate signals from a reflector. If this reflector is a single porosity, its physics that this kind of reflector will often get a pass due to poor ultrasound reflection, where with RT, where you can see such a reflector much better, you will get a no pass.

Think about it, in UTPA you evaluate signals from a reflector. If this reflector is a side wall lack of fusion, its physics that this kind of reflector will often get a no pass due to great ultrasound reflection, where with RT, where you can't see such a reflector, you will get a pass.

 
 Reply 
 
Levi Porter
R & D,
Dacon Inspection Technologies, Thailand, Joined Jan 2017, 39

Levi Porter

R & D,
Dacon Inspection Technologies,
Thailand,
Joined Jan 2017
39
11:30 Nov-26-2019
Re: Phased Array vs RT
In Reply to Naser at 20:25 Nov-25-2019 (Opening).

Hi Naser,
RT & UT have very different acceptance criteria. It is common for UT to accept porosity and possibly slag / inclusions because of the low amplitude reflections they return.

RT has a simple acceptance: if defect greater than X distance: reject. (bit of paraphrasing don't crucify me RT guys)

I won't pretend to know the mechanical engineering calculations for choosing these acceptance criteria, but I feel confidant that ASME engineers have done a good job with their creation.

 
 Reply 
 
Muhammad Arshad
Muhammad Arshad
12:01 Nov-26-2019
Re: Phased Array vs RT
In Reply to Levi Porter at 11:30 Nov-26-2019 .

I would like to say that comparing two different NDT techniques for acceptance criteria doesn't make sense because acceptance criteria is always based on the technique's sizing capabilities instead of detection capabilities.

 
 Reply 
 
Jean-Francois Martel
Engineering, Lead NDE Scientist
Nucleom, Inc., Canada, Joined Jun 2010, 5

Jean-Francois Martel

Engineering, Lead NDE Scientist
Nucleom, Inc.,
Canada,
Joined Jun 2010
5
14:47 Nov-26-2019
Re: Phased Array vs RT
In Reply to Muhammad Arshad at 12:01 Nov-26-2019 .

I had this kind of conversation with multiple clients and one thing to keep in mind is that NDE methods are complementary. Each have their strength and weaknesses. RT is usually better with handling porosity but may miss other type of defects like tight cracks where UT has often higher probability of detection.
So, according to the requirements, you may want to do both PAUT and RT or complement your PAUT with other UT techniques like TOFD.

 
 Reply 
 
Carlos Andrés Galán
NDT Inspector,
UIS - Universidad Industrial de Santander, Colombia, Joined Oct 2014, 31

Carlos Andrés Galán

NDT Inspector,
UIS - Universidad Industrial de Santander,
Colombia,
Joined Oct 2014
31
04:33 Nov-28-2019
Re: Phased Array vs RT
In Reply to Jean-Francois Martel at 14:47 Nov-26-2019 .

Download

Hi everybody


I manufactured three welds with cracks, incomplete penetration and lack of fusion between the base material and the contribution material, in 6 mm thick plates. The welding was performed with GTAW processes and the inspection was carried out with conventional X-rays, obtaining high contrast and phased array ultrasonic testing, with an omniscan equipment, probe 5L16, S-scan (I share images C-scan), with TCG sizing curve, both following code procedure ASME.

The first thing is that all defects were detected by both methods.
The objective was not to apply acceptance criteria, the objective was to compare the dimensions obtained by the two methods, and we conclude that if there are differences, which are complementary methods, that the x-ray images are very easy to interpret, which despite being Lack of fusion in the bevel if they were detected by x-rays, and that by phased array requires coupling on both sides of the weld.

I add images for you to compare.

Carlos
 
 Reply 
 
Naser
Iran, Joined Nov 2018, 4

Naser

Iran,
Joined Nov 2018
4
21:44 Nov-29-2019
Re: Phased Array vs RT
In Reply to Carlos Andrés Galán at 04:33 Nov-28-2019 .

zoom image
Hi Carlos
The detectability could be compair for different methods. But the acceptance criteria not. Plz read paragraph 344.6.2 in asme b31.3.
1
 
 Reply 
 
Carlos Andrés Galán
NDT Inspector,
UIS - Universidad Industrial de Santander, Colombia, Joined Oct 2014, 31

Carlos Andrés Galán

NDT Inspector,
UIS - Universidad Industrial de Santander,
Colombia,
Joined Oct 2014
31
17:43 Dec-02-2019
Re: Phased Array vs RT
In Reply to Naser at 21:44 Nov-29-2019 .

Hi naser

I agree with you, I just wanted to show that the criteria can be ambiguous when the dimensions obtained by the tests are different from the real defect.

 
 Reply 
 
Levi Porter
R & D,
Dacon Inspection Technologies, Thailand, Joined Jan 2017, 39

Levi Porter

R & D,
Dacon Inspection Technologies,
Thailand,
Joined Jan 2017
39
05:19 Dec-03-2019
Re: Phased Array vs RT
In Reply to Carlos Andrés Galán at 04:33 Nov-28-2019 .

Hi Carlos,
Thank you for sharing this interesting report. Can you share more details, such as part thickness, weld geometry, ultrasonic scan plans, sizing methods, defect production methods and any other pertinent information? This data you have could be quiet a valuable teaching tool and I want to understand the methods with more clarity.

1
 
 Reply 
 
Carlos Andrés Galán
NDT Inspector,
UIS - Universidad Industrial de Santander, Colombia, Joined Oct 2014, 31

Carlos Andrés Galán

NDT Inspector,
UIS - Universidad Industrial de Santander,
Colombia,
Joined Oct 2014
31
16:54 Dec-03-2019
Re: Phased Array vs RT
In Reply to Levi Porter at 05:19 Dec-03-2019 .

Hi levi

Here are some details:
Thickness: 6mm
bezel: 30 °
welding process: GTAW and SMAW
Base metal 1: AISI 316
Base metal 2: ASTM A36
Input metal: ER 309L 3/32 ''
Root Separation: 3mm

The defects were generated by qualifying WPS, materials were selected according to the schaeffler diagram to be within the martensistic zone with dilution of approximately 45% and with material temperature changes.

The lack of fusion was achieved by lowering the intensity of the arc.

The lack of penetration was achieved with direct current, direct polarity and varying offset speed.

If there are any doubts I can go into more detail,

bye

 
 Reply 
 

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