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Technical Discussions
Anandh Perumal
India, Joined Jan 2015, 19

Anandh Perumal

India,
Joined Jan 2015
19
13:26 Oct-13-2016
Phased Array Ultrasonic testing

What is the minimum thickness upto which PAUT can be carried out?

 
 Reply 
 
Diego
Consultant,
Freelance, Spain, Joined May 2013, 188

Diego

Consultant,
Freelance,
Spain,
Joined May 2013
188
18:13 Oct-13-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 13:26 Oct-13-2016 (Opening).

For weld, the same thickness as for the conventional technique; generally 6 mm.

 
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Anandh Perumal
India, Joined Jan 2015, 19

Anandh Perumal

India,
Joined Jan 2015
19
06:07 Oct-14-2016
Re: Phased Array Ultrasonic testing
In Reply to Diego at 18:13 Oct-13-2016 .

One of the agency person told upto 3mm also possible provided a reference block with defect hole is available.job is economizer,superheater coils in boiler pressure parts.please advice,

 
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Diego
Consultant,
Freelance, Spain, Joined May 2013, 188

Diego

Consultant,
Freelance,
Spain,
Joined May 2013
188
13:57 Oct-14-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 06:07 Oct-14-2016 .

It is possible. But generally it is not required to perform UT on welded joints with a thickness > 6 mm. You should bear in mind the code, standards or specifications employed for the design manufacture and inspection

 
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Anandh Perumal
India, Joined Jan 2015, 19

Anandh Perumal

India,
Joined Jan 2015
19
12:25 Oct-18-2016
Re: Phased Array Ultrasonic testing
In Reply to Diego at 13:57 Oct-14-2016 .

For economiser coils the O.D of pipe is 44.5mm and thickness 4.5mm how average time will be required for each joint.i have to make comparison between PAUT and RT.Please suggest

 
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SAURAV
NDT Inspector,
Singapore, Joined May 2014, 14

SAURAV

NDT Inspector,
Singapore,
Joined May 2014
14
18:30 Oct-18-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 12:25 Oct-18-2016 .

yes, on economizer tubes it is possible for such thickness's with olympus solutions. I have personally inspected more than 20,000 joints on malaysian power plants with such technique. In ideal situation it will take only maximum 30seconds to record data. However it will take time to convert, analyze and do reporting. In my shutdown experience we have done around 180 joints each 12hour shifts. Our clients were very happy with the results. Please mail me know if you want more information on this.

 
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Anandh Perumal
India, Joined Jan 2015, 19

Anandh Perumal

India,
Joined Jan 2015
19
07:43 Oct-19-2016
Re: Phased Array Ultrasonic testing
In Reply to SAURAV at 18:30 Oct-18-2016 .

Thanks,Mr Saurav but for this small thickness jobs what is the effect of dead zone because here too transmission are receiving will be there,pulse also same

 
 Reply 
 
Daniel Braun
Daniel Braun
15:51 Oct-19-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 07:43 Oct-19-2016 .

In case of using suitable probe and the proper settings of the PA pulser - receiving / proper scan plan provided it should not be a problem to inspect the welds for 3 mm WT and even less. For example refer to the the page 3 at http://www.sonotronndt.com/APPLICATIONS/PA_APPS/PA_APP_STORE/ISONIC_PA_EXPERT_EXPERT_A.pdf
This is a sample from the automotive industry, the parent material thickness is 2.8 mm, you may find the instrument file related to this case inside the archive:
http://www.sonotronndt.com/Images/PA_UT_APPS/EXPERT_A/EXPERT_A_TRANZIT_PA_UT_EXAMPLES.zip
the file name is: EXPERT_A_WELDED_SHAFT.asb - you may open the file and play back all A-Scans comprised, see the probe data and the instrument settings using ISONIC PA Office SW package available for the free download at http://www.sonotronndt.com/support.htm
Also the scribe mark detection for the aircraft skin is well performed with the use of PA modality, the skin thickness does not exceed 3...4 mm

 
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Shahid Nisar
Engineering,
Saudi Arabia, Joined Feb 2009, 136

Shahid Nisar

Engineering,
Saudi Arabia,
Joined Feb 2009
136
07:05 Oct-20-2016
Re: Phased Array Ultrasonic testing
In Reply to Daniel Braun at 15:51 Oct-19-2016 .

At this stage with so advancement in technologies but on other side lagging of respective codes, we can can confidently say PA of low thickness weld(t>6mm) possible with good POD subjected to performer skills and expertise but not in conformance to ASME construction codes whatsoever the results and client satisfactions are. However ISO standards allow UT/PA for low thickness welds (t>6mm).

 
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Anandh Perumal
India, Joined Jan 2015, 19

Anandh Perumal

India,
Joined Jan 2015
19
11:59 Oct-20-2016
Re: Phased Array Ultrasonic testing
In Reply to Shahid Nisar at 07:05 Oct-20-2016 .

Mr Shahid,Please provide ISO standard number which supports thickness >6mm if possible please attach.because i have only ASME B31.1 which accepts UT above 12.7mm

 
 Reply 
 
Shahid Nisar
Engineering,
Saudi Arabia, Joined Feb 2009, 136

Shahid Nisar

Engineering,
Saudi Arabia,
Joined Feb 2009
136
07:07 Oct-21-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 11:59 Oct-20-2016 .

ISO 13588 is for PAUT of t>6 mm. Sorry the document can not be shared because of Copyright issue.

 
 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
13:58 Oct-21-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 11:59 Oct-20-2016 .

Anandh, you seemed to imply that ASME does not allow ultrasonic inspection of wall thickness under 12.7mm. To substantiate your position you referenced ASME B31.1 (Power Piping). I could find no such limitation in my copy of ASME B31.1. Also note, there is no mention of thickness limitation in ASME V (Nondestructive testing) where you see in Fig. 434.2.1 the reference to the calibration block for "Up to 25mm".
A similar indication of no lower limit is in B31.3 in Para 344.6.1 where reference is made to ultrasonic testing of pipe sizes less than or equal to NPS 2 (DN 50).
In all cases, anyone doing UT in accordance with ASME Sec.V can be subject to demonstrating the efficacy of the technique to the satisfaction of the Authorised Inspector as per ASME V Art. 1 T-150.
ISO 13588 specifically states that it is for the application of phased-array UT on full penetration welded joints of simple geometry in plates, pipes, and vessels, where both the weld and parent material are low-alloyed carbon steel with thickness greater than or equal to 6mm.
However, just because a standard permits a defined thickness to be examined is no assurance that the welds should be examined by UT (either phased-array or mono-element). A significant limiting factor in the efficacy of UT on thin-walled welds is the weld-cap geometry.

 
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Anandh Perumal
India, Joined Jan 2015, 19

Anandh Perumal

India,
Joined Jan 2015
19
09:04 Oct-22-2016
Re: Phased Array Ultrasonic testing
In Reply to Ed Ginzel at 13:58 Oct-21-2016 .

Download

Mr Ed Ginzel,Please find the attached copy from ASME B31.1 which specifies thickness 12.7mm.
I referred B31.3 para 344.6.1 too which is not specifying the schedule of pipes which refer to thickness.
I agree with Mr Diego who replied that if we can catch an echo from a reference block of our required diameter and thickness with a particular probe , accepted by our customer we can proceed further.but my doubts are because of dead zone( transmission and receiving by same crystal) and upto Near zone of that particular probe will the indication will it be clear?for such a small thickness.because even for thickness measurement below 10mm we are using TR probe.
As per you ISO 13588 accepts UT for thickness upto 6mm for Carbon steel and our job includes Low alloy steel(SA 335 P11&P22)
please explain "limiting factor in efficacy of UT on thin walled is weld cap geometry" you mean bevel angle ,reinforcement etc
 
 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
16:07 Oct-22-2016
Re: Phased Array Ultrasonic testing
In Reply to Anandh Perumal at 09:04 Oct-22-2016 .

zoom image



Anandh, your reference is to a Code Case (168) and it is NOT to the Code ASME B31.1. In addition, your reference is to Code Case 168 which, if you read the top lines of your posting, was published in 1997 and expired in 2000. Go to the NDT.net forum topic at http://www.ndt.net/forum/thread.php?&rootID=12417 and there you will find a post by Wilyan Safitra that includes a newer Code Case, CC179 which changed the question and the condition provided by the committee. CC179 asked:
Under what conditions and limitations may an ultrasonic examination be used in lieu of radiography on fabrication welds in materials with a thickness of 1⁄2 in. or less when a volumetric examination is required by Table 136.4 of ASME B31.1?
The reply was UT could be used at any time on B31.1 welds providing all the CC179 conditions were met.
But CC179 is also old so perhaps it would be best to review the examination requirements as per Table 136.4 in ASME B31.1 and obtain the latest applicable Code Case before assuming the 19mm lower limit.

As for limitations, the normal pulse-echo inspection using a refracting wedge may have a signal due to interaction at the wedge/part interface, but it is not exactly comparable to the 0° ringdown. The interaction occurs over a period of time; from the time for the lower portion of the beam to reach the interface until the upper portion of the angled incident beam reaches the interface. Depending on the surface roughness, the aperture dimensions and bandwidth, duration of this interface signal will vary and can cause annoying signals if you are attempting to resolve flaws in the first few millimetres of entry. In the uploaded image I used Civa to model a beam from a 70° S-mode probe with 5MHz nominal frequency. I placed the probe on a wedge that has the same dimensions as a miniature wedge I have in my lab. Then I configured a weld profile for a 2 inch NPS pipe with a 6.35mm wall and put a small weld reinforcement on the cap and root. The image illustrates how the weld reinforcement prevents the nose of the wedge from approaching the weld. As a result, the centre of the beam does not reach the root centreline. But we also see that the centre of beam will never enter the root region unless the operator uses 1.5 skips. By that time, the beam is so wide you will struggle to sort out the signal origins and probably not even be able to discriminate between cap and root. As for the "dead zone" you were worried about, you see that in the first half-skip portion of the beam, it has not even reached the weld metal. So even if you had a 15mm ringdown due to the interface "dead zone" this would end before the beam had reached weld metal.
My point was that the ability to get a USEFUL signal will probably present a greater issue than the concerns for a dead zone when attempting to examine welds in thin walled materials.
 
 Reply 
 
Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 227

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
227
02:28 Oct-23-2016
Re: Phased Array Ultrasonic testing
In Reply to Ed Ginzel at 16:07 Oct-22-2016 .

Very helpful post, Ed.

 
 Reply 
 

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