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Technical Discussions
ian
ian
10:54 Jun-12-2012
PAUT on Stainless Steel

Hello, can anyone advise as to whether PAUT has been carried out (routinely) on stainless steel pipework butt welds in the range 5.6mm to 20mm

Thanks

 
 Reply 
 
Sudheer Jai Krishnan
Sudheer Jai Krishnan
19:25 Jun-12-2012
Re: PAUT on Stainless Steel
In Reply to ian at 10:54 Jun-12-2012 (Opening).

Hello Ian,

Greetings. Yes, it can be definitely performed.I have carried out the same where the piping thickness was 6.5mm to 20mm.

Regards

Sudheer Jai Krishnan

 
 Reply 
 
massimo carminati
Consultant, AUT specialist
IMG Ultrasuoni Srl, Italy, Joined Apr 2007, 691

massimo carminati

Consultant, AUT specialist
IMG Ultrasuoni Srl,
Italy,
Joined Apr 2007
691
20:25 Jun-12-2012
Re: PAUT on Stainless Steel
In Reply to ian at 10:54 Jun-12-2012 (Opening).

As Sudheer said, SS welds can be successfully tested with Paut. The most important advandage is the signal to noise ratio improvment and the possibility to discriminate flaw indcation from background noise on b-scan or side and top view. It is fundamental to produce welds mock-ups closest to real welds in terms of bevels, weld material and welding process, but this is true also for standard ut. Remeber you need high energy and narrow beams, so, "big" pa probes and longitudinal waves.

 
 Reply 
 
Csaba Hollo
,
Retired, Canada, Joined Feb 2010, 301

Csaba Hollo

,
Retired,
Canada,
Joined Feb 2010
301
20:33 Jun-12-2012
Re: PAUT on Stainless Steel
In Reply to ian at 10:54 Jun-12-2012 (Opening).

As with conventional testing using UT shear beams in Austenitic weldments, you may have some difficulty with the anisotropic nature of the weld.

Acoustic velocity, refraction, damping, and attenuation are all factors affecting the beam.

It is advisable to fabricate calibration samples with sensitivity targets placed in and through the weld from a sound path perspective.

1
 
 Reply 
 
ian
ian
21:23 Jun-12-2012
Re: PAUT on Stainless Steel
In Reply to Csaba Hollo at 20:33 Jun-12-2012 .

Thanks for the replies, can you tell me the codes that you were working to please?

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

andrew cunningham

NDT Inspector
Canada,
Joined Jun 2008
238
23:49 Jun-12-2012
Re: PAUT on Stainless Steel
In Reply to Sudheer Jai Krishnan at 19:25 Jun-12-2012 .

Hi Saheer
May I ask, what was the smallest discontinuity you have found while testing the stainless steel welds pipe welds.

Andrew

 
 Reply 
 
ian
ian
00:15 Jun-13-2012
Re: PAUT on Stainless Steel
In Reply to andrew cunningham at 23:49 Jun-12-2012 .

i would also be interested on peoples thoughts on how to perform transverse scans on st/st small bore pipework

 
 Reply 
 
Sudheer Jai Krishnan
Sudheer Jai Krishnan
06:55 Jun-13-2012
Re: PAUT on Stainless Steel
In Reply to andrew cunningham at 23:49 Jun-12-2012 .

2mm.

 
 Reply 
 
Andrey Bazulin
R & D, -
Scientific Center ECHO+, Russia, Joined Sep 2006, 58

Andrey Bazulin

R & D, -
Scientific Center ECHO+,
Russia,
Joined Sep 2006
58
22:24 Jun-15-2012
Re: PAUT on Stainless Steel
In Reply to ian at 10:54 Jun-12-2012 (Opening).

We use 4 and 5 MHz shear waves AUT on SS girth welds with wall thickness 12-18 mm both with conventional probes (with FT-SAFT) and with PAUT.
But the flaw sizing is reliable for flaws (cracks) in HAZ or at the weld chamfer.

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
15:51 Jun-17-2012
Re: PAUT on Stainless Steel
In Reply to Sudheer Jai Krishnan at 06:55 Jun-13-2012 .

Sudheer

2mm defect in stainless steel 6,5 to 20mm wall thickness? is that equivalent reflector size (FBH) or vertical height?

What probes did you use?

Nigel

 
 Reply 
 
Sudheer Jai Krishnan
Sudheer Jai Krishnan
18:26 Jun-17-2012
Re: PAUT on Stainless Steel
In Reply to Nigel Armstrong at 15:51 Jun-17-2012 .

It was the 2mm SDH taken as a reference, and the probe used was 5L16 with N60S. It was a screening to find out the LF's and cracks in the weldments as there was a problem reported

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
02:31 Jun-19-2012
Re: PAUT on Stainless Steel
In Reply to Sudheer Jai Krishnan at 18:26 Jun-17-2012 .

See J Ogilvy's paper on austenitic weld inspection (Journal of BINDT circa 1988) for beam-skewing effects. Also Krautkramer booklet on the same subject. Both advocate the use of twin-crystal longitudinal wave angle probes

Is there a manufacturer who produces wedges to introduce angle longitudinal wave (like ToFD wedges I suppose but with PA transducers).

Recently a major stainless steel vessel producer took advice (from an established not-for-profit source) on replacing RT with PAUT and decided to stick with RT. It seems as if PAUT is not yet ready to conquer the world. How about ToFD on stainless? I realise the lateral and backwall dead zones would need to be addressed.

 
 Reply 
 
Sudheer Jai Krishnan
Sudheer Jai Krishnan
06:35 Jun-19-2012
Re: PAUT on Stainless Steel
In Reply to Nigel Armstrong at 02:31 Jun-19-2012 .

Hello Nigel,

But the defects which i have reported in the welds were opened up by grinding and the good things was the defects were really present. I also didnt found any noise as the thickness was low.

Then as you asked, Longitudinal Wedges are available for PA probes and one of them i have used is SA10-N60L with 5L16-A10 transducer.

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
12:20 Jun-19-2012
Re: PAUT on Stainless Steel
In Reply to Sudheer Jai Krishnan at 06:35 Jun-19-2012 .

This article by Olympus covers UT testing of austenitics:

http://www.olympus-ims.com/en/applications/dual-matrix-array-inspection/

supports what Massimo writes, with the caveat as Csaba posits that replica weld specimens with known defects must be available to gauge beam skew.

Sidewall and root inspection without traversing the columnar grains of the deposited weld metal may be reliable. Otherwise the aforementioned grain structure noise and beam-skewing complicate the test.

Andrey, the short wavelength of the 4 - 5 MHz shear wave must make traversing the austenitic weld metal very imprecise and noisy. I have never knowingly worked with Fourier Transforms and Synthetic Aperture Focusing - maybe in the future these techniques will be taught on a Level 3 course, otherwise I believe its learn on the job.

Has anyone experience of ToFD on austentic welds?

 
 Reply 
 
Sudheer Jai Krishnan
Sudheer Jai Krishnan
12:50 Jun-19-2012
Re: PAUT on Stainless Steel
In Reply to Nigel Armstrong at 12:20 Jun-19-2012 .

Dear Nigel ,

Attached is one of the screen shot from Omni when i have scanned the 10" pipe. Please find the position of the probe also and the cracking was a transverse one.

 
 Reply 
 
Andrey Bazulin
R & D, -
Scientific Center ECHO+, Russia, Joined Sep 2006, 58

Andrey Bazulin

R & D, -
Scientific Center ECHO+,
Russia,
Joined Sep 2006
58
18:25 Jun-19-2012
Re: PAUT on Stainless Steel
In Reply to Sudheer Jai Krishnan at 12:50 Jun-19-2012 .

Nigel.

As far as I know - the inspection of austenitic welds by TOFD is not relieable. Round-robin tests (in Germany?) in 1980th showed bad reliability.

What for inspection with S-waves and 4-5 MHz - a priory detected flaws were located in weld root area so detection of flaws with height about 25% of wall thickness throught weld was considered.

Also we used FT-SAFT with 2.5 MHz two-mode (shear and longitudinal) inspection of austenitic welds with wall thickness up to 60 mm (partly in ITER project). Lacks of fusion and artifical flaws were detected.

What for FT-SAFT - is is not so far from PA S-scan imaging. But with FT-SAFT one can
a) focus to any point of object
b) take into account reflections from surface and bottom and wave type conversion
c) use 3D data processing to increase resolution along weld axis

Here is some papers with our experience:
http://www.ndt.net/search/link.php?id=7573&file=article/defektoskopie2008/papers/321.pdf
http://www.ndt.net/search/link.php?id=6500&file=article/wcndt2008/papers/254.pdf

 
 Reply 
 
M Balaji
M Balaji
16:25 Aug-03-2018
Re: PAUT on Stainless Steel
In Reply to massimo carminati at 20:25 Jun-12-2012 .

Hello,

We planning to do PAUT on convection coils of Hydrogen reformer. Tube Size is 3" and 5.49mm thk Material grade ASTM A 312 TP 347H.

any one can advise how to proceed and what are the requirements
Please guide

 
 Reply 
 
gopi
,
India, Joined Jul 2018, 1

gopi

,
India,
Joined Jul 2018
1
02:47 Aug-05-2018
Re: PAUT on Stainless Steel
In Reply to M Balaji at 16:25 Aug-03-2018 .

please follow the asnt procedure
instructions

























 
 Reply 
 

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