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- since 1996 -
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Technical Discussions
Dhiliban
Other, QA/QC engineer
L&T HCP, India, Joined May 2016, 16

Dhiliban

Other, QA/QC engineer
L&T HCP,
India,
Joined May 2016
16
10:37 Jul-04-2016
UT thickness measurement with paint

Dear Specialists
While using UT for scanning for weld we are removing the paint, but in the case of thickness measurement,it is done over the coated pipes,but we are getting the accurate thickness(thickness of pipe+thick of coating)value,how the UT waves passes through the paint without reflection

 
 Reply 
 
John
Consultant,
Sonomatic Ltd, United Kingdom, Joined Apr 2003, 14

John

Consultant,
Sonomatic Ltd,
United Kingdom,
Joined Apr 2003
14
12:23 Jul-04-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 10:37 Jul-04-2016 (Opening).

When carrying out thickness readings through paint, you should measure between the 1st and 2nd BWE's to remove the paint delay.

 
 Reply 
 
Dhiliban
Other, QA/QC engineer
L&T HCP, India, Joined May 2016, 16

Dhiliban

Other, QA/QC engineer
L&T HCP,
India,
Joined May 2016
16
18:57 Jul-04-2016
Re: UT thickness measurement with paint
In Reply to John at 12:23 Jul-04-2016 .

Thanks Jhon

It is possible to angle beam scanning of pipe welds over paint.

 
 Reply 
 
Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 747

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
747
19:56 Jul-04-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 18:57 Jul-04-2016 .

Case by case
Tight and thin paint - possible
Loose or thick paint - not recommended and may not be not possible

 
 Reply 
 
Paul Holloway
Consultant,
Holloway NDT & Engineering Inc , Canada, Joined Apr 2010, 191

Paul Holloway

Consultant,
Holloway NDT & Engineering Inc ,
Canada,
Joined Apr 2010
191
01:36 Jul-05-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 18:57 Jul-04-2016 .

You should perform a transfer correction if performing examination through paint.

 
 Reply 
 
Shawn
Shawn
14:30 Jul-06-2016
Re: UT thickness measurement with paint
In Reply to John at 12:23 Jul-04-2016 .

dont you mean the 2nd and 3rd?
As the 1st will include the paint.

 
 Reply 
 
John
Consultant,
Sonomatic Ltd, United Kingdom, Joined Apr 2003, 14

John

Consultant,
Sonomatic Ltd,
United Kingdom,
Joined Apr 2003
14
14:52 Jul-06-2016
Re: UT thickness measurement with paint
In Reply to Shawn at 14:30 Jul-06-2016 .

Think about it!
1st to 2nd doesn't include the paint.

 
 Reply 
 
Dhiliban
Other, QA/QC engineer
L&T HCP, India, Joined May 2016, 16

Dhiliban

Other, QA/QC engineer
L&T HCP,
India,
Joined May 2016
16
16:45 Jul-06-2016
Re: UT thickness measurement with paint
In Reply to John at 14:52 Jul-06-2016 .

One basic principle of UT wave propagation seems bit contradicting in material inspection paint inspection

The density of paint is very less when compared to that of metals ex Carbon steels,SS since comparatively the Refractive index at the surface will be bit high.So there UT waves should reflect,but practically it reflects a bit and refraction is more(most of the waves pass through)

Theory and practical seems bit contracting as per my knowledge,,Please someone clear this concept

 
 Reply 
 
Philippe
R & D, Sonatest
Sonatest, Canada, Joined Jan 2015, 37

Philippe

R & D, Sonatest
Sonatest,
Canada,
Joined Jan 2015
37
19:35 Jul-06-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 16:45 Jul-06-2016 .

As John says: 1st and 2nd back wall echo! It is normally the highest serie of peaks in the scan.

Imagine the sound travel path and assign your peaks in your A-scan. You are going to set your gates easily after!

Good luck ,

Phil

 
 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
07:10 Jul-10-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 16:45 Jul-06-2016 .

Measuring between multiple echoes is like "adding" the paint thickness to probe delay.

 
 Reply 
 
Jen
Sales,
Cygnus Instruments Ltd, United Kingdom, Joined Apr 2016, 2

Jen

Sales,
Cygnus Instruments Ltd,
United Kingdom,
Joined Apr 2016
2
13:25 Jul-11-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 10:37 Jul-04-2016 (Opening).

Please see this page from our website on how Cygnus multiple echo thickness gauges ignore the coating
http://www.cygnus-instruments.com/technology/multiple-echo-measuring-mode/

 
 Reply 
 
tariq
NDT Inspector,
Association sonatrach & British Petroleum & Statoil, Algeria, Joined Jun 2014, 10

tariq

NDT Inspector,
Association sonatrach & British Petroleum & Statoil,
Algeria,
Joined Jun 2014
10
18:33 Sep-10-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 10:37 Jul-04-2016 (Opening).

Hello
for the reason of big different between the impedance of metal and the paint (Zsteel>> Z paint), so the reflection of waves is not considerable which means that more than 95% of sound pass through the paint to the metal
but i think the question should be HOW to remove the paint thickness during measuring to get an accurate thickness of metal,
here i say that there are a setting can be done to UT apparatus (Epoch600) for instance to get only the thickness of metal, the method name is ECHO to ECHO method
which based at the calculation of the difference between the first echo and the second one instead of calculate the difference between the initial echo and the first one

 
 Reply 
 
Daniel Braun
Daniel Braun
07:47 Sep-11-2016
Re: UT thickness measurement with paint
In Reply to Dhiliban at 10:37 Jul-04-2016 (Opening).

Multi-echo measurement is the way to remove the thickness of the paint / coating or other intermediate material between the probe and part under test - ISONIC utPod instrument allows the same in the automatic mode with the use of either single or dual element probes: http://www.sonotronndt.com/utpod.htm - on opening the link click on the >Through Paint> tab, the multiple echoes are recognized automatically, no need in the second gate, the videos are also available here
https://www.youtube.com/watch?v=I84sOXJE9Jk - the sample with the paint / coating of several types / thickness of the layer
https://www.youtube.com/watch?v=TbQUBogXTcA - measuring of the thickness of the tube wall at the no access side through the water filling the tube

 
 Reply 
 

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