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- since 1996 -
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Technical Discussions
Dean DeLeo
Dean DeLeo
01:55 Mar-24-2005
NDT for UT measurement and Crack Detection

Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.


    
 
 Reply 
 
DJ Kallhof
DJ Kallhof
03:55 Mar-28-2005
Re: NDT for UT measurement and Crack Detection
The crack detection could easily be done with a dry powder mag and an AC yoke. Do not use a DC yoke as it will not allow for particle mobility. I have done similar inspections at a power house construction site that was NRC approved. If you are uneasy with the simplicity of the answer just create a crack sample made of the same material and coat it as thick or thicker than the actual work pieces. Prove your technique to yourself or to the customer. Don't forget the 10 lb weight lift to qualify the yoke.

----------- Start Original Message -----------
: Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
------------ End Original Message ------------




    
 
 Reply 
 
Borja Lopez
Director
Innerspec Technologies, USA, Joined Jun 2002, 36

Borja Lopez

Director
Innerspec Technologies,
USA,
Joined Jun 2002
36
07:51 Mar-28-2005
Re: NDT for UT measurement and Crack Detection
----------- Start Original Message -----------
: Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
------------ End Original Message ------------

You can do both thickness and weld inspection using Ultrasonic EMAT


    
 
 Reply 
 
Zeki Cosku Gokce
Zeki Cosku Gokce
08:45 Mar-29-2005
Re: NDT for UT measurement and Crack Detection
----------- Start Original Message -----------
: Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
------------ End Original Message ------------

Can you give more detail? Can you access both sides of the part also what is the thickness of the part?


    
 
 Reply 
 
Martin Lugg
Consultant,
TSC Inspection Systems, United Kingdom, Joined Nov 2000, 27

Martin Lugg

Consultant,
TSC Inspection Systems,
United Kingdom,
Joined Nov 2000
27
05:41 Mar-29-2005
Re: NDT for UT measurement and Crack Detection
The ACFM technique was developed precisely for detecting cracks at welds in carbon steel under non-conducting coatings. In fact, ACFM can detect through much thicker coatings, and can also provide defect sizes.

See our website www.tscinspectionsystems.com for more information.
----------- Start Original Message -----------
: Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
------------ End Original Message ------------




    
 
 Reply 
 
J. Mark Davis
Teacher, And Consultant
University of Ultrasonics, Birmingham, Alabama, USA, Joined Mar 2000, 85

J. Mark Davis

Teacher, And Consultant
University of Ultrasonics, Birmingham, Alabama,
USA,
Joined Mar 2000
85
07:54 Mar-29-2005
Re: NDT for UT measurement and Crack Detection
What is the thickness of the carbon steel material.

What is the PTFE materail.

What is your critical flaw size?

ID or OD connected cracks are to be detected?

ID or OD Creeping Wave techniques will help with crack detection and qualitative sizing.

J. Mark Davis


----------- Start Original Message -----------
: : Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
: You can do both thickness and weld inspection using Ultrasonic EMAT
------------ End Original Message ------------




    
 
 Reply 
 
Joe Buckley
Joe Buckley
08:05 Mar-29-2005
Re: NDT for UT measurement and Crack Detection

If the coating is only 50 microns or so it seems unlikely to interfere with most NDT methods, MPI, Eddy current (inc ACFM) and Radiography would barely notice it was there, For UT methods, assuming the coating is well adhering its not much more than a thick layer of couplant. It would always be a good idea to check with a coating gauge that the thickness as you think. for really accurate UT thickness measurement you could apply a correction factor based on the relative velocities, (or just subtract 0.1mm from the indicated reading!)

Exotic methods may be useful for other reasons, But if its just a standard weld a standard method should be enough.
----------- Start Original Message -----------
: Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
------------ End Original Message ------------




    
 
 Reply 
 
Dean DeLeo
Dean DeLeo
05:19 May-09-2005
Re: NDT for UT measurement and Crack Detection
----------- Start Original Message -----------
: : Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
: Can you give more detail? Can you access both sides of the part also what is the thickness of the part?
------------ End Original Message ------------

Thanks all for the feedback.
The mentioned equipment is a jacketed vessel where the product inside is waxy-like polymer.The internal part of the vessel is coated with 60-micron teflon. The intention is to avoid removing the teflon coating. Unfortunately, the waxy-like polymer is also difficult to remove without damaging the coating.Thus, is there any available NDT technique to do NDT inspection with these parameters in place (teflon+unknown thickness of polymer). The inspection to be conducted is to know the remaining thickness for internal vessel wall (remember the outside is jacketed) and to inspect the integrity of the internal wall's weldment.

Any info would very much appreciated. Thanks.


    
 
 Reply 
 
D
D
06:48 May-09-2005
Re: NDT for UT measurement and Crack Detection
Alternating Current Field Measurement (ACFM) can provide a good quality inspection without removing the coating but it will only detect near surface defects. These methods are used commonly on painted oil rig supports etc with well proven capabilities


    
 
 Reply 
 
Martin Lugg
Consultant,
TSC Inspection Systems, United Kingdom, Joined Nov 2000, 27

Martin Lugg

Consultant,
TSC Inspection Systems,
United Kingdom,
Joined Nov 2000
27
07:15 May-09-2005
Re: NDT for UT measurement and Crack Detection
The ACFM technique will be able to inspect the weld surface for cracks through several millimetres of coating. See our web-site for information on performance when inspecting through coatings - and contact details for your local agent.

----------- Start Original Message -----------
: : : Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
: : Can you give more detail? Can you access both sides of the part also what is the thickness of the part?
: Thanks all for the feedback.
: The mentioned equipment is a jacketed vessel where the product inside is waxy-like polymer.The internal part of the vessel is coated with 60-micron teflon. The intention is to avoid removing the teflon coating. Unfortunately, the waxy-like polymer is also difficult to remove without damaging the coating.Thus, is there any available NDT technique to do NDT inspection with these parameters in place (teflon+unknown thickness of polymer). The inspection to be conducted is to know the remaining thickness for internal vessel wall (remember the outside is jacketed) and to inspect the integrity of the internal wall's weldment.
: Any info would very much appreciated. Thanks.
------------ End Original Message ------------




    
 
 Reply 
 
Frank Lund
R & D,
United Kingdom, Joined Apr 2005, 219

Frank Lund

R & D,
United Kingdom,
Joined Apr 2005
219
01:16 May-10-2005
Re: NDT for UT measurement and Crack Detection
The electromagnetic array and field gradient imaging techniques offered by NEWT International would be ideal for your application. We have done work through coatings before. Please see our web site or contact sgreenall@lizard.co.uk


----------- Start Original Message -----------
: : : Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
: : Can you give more detail? Can you access both sides of the part also what is the thickness of the part?
: Thanks all for the feedback.
: The mentioned equipment is a jacketed vessel where the product inside is waxy-like polymer.The internal part of the vessel is coated with 60-micron teflon. The intention is to avoid removing the teflon coating. Unfortunately, the waxy-like polymer is also difficult to remove without damaging the coating.Thus, is there any available NDT technique to do NDT inspection with these parameters in place (teflon+unknown thickness of polymer). The inspection to be conducted is to know the remaining thickness for internal vessel wall (remember the outside is jacketed) and to inspect the integrity of the internal wall's weldment.
: Any info would very much appreciated. Thanks.
------------ End Original Message ------------




    
 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 522

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
522
01:34 May-10-2005
Re: NDT for UT measurement and Crack Detection
I think we need to know a bit more about the thickness of this polymer - "unknown thickness" doesn't give us enough to draw any conclusions from.
Are we talking microns (i.e comparable to the PTFE coating thickness) or significantly more.

Any method / procedure will have a maximum allowable thickness, so you will need to equip yourself with a coating gauge to measure it and be prepared to remove some of the polymer if the thickness is excessive.

Any of the main techniques discussed (UT, ET, ACFM) can 'probably' be applied through coatings of a milimeter or more, but as the coating thickness increases the results will become less reliable.

For UT the propeties of the polymer material will also be important

I think this discussion has progressed to the point where we need more specific information.

Joe

----------- Start Original Message -----------
: : : Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
: : Can you give more detail? Can you access both sides of the part also what is the thickness of the part?
: Thanks all for the feedback.
: The mentioned equipment is a jacketed vessel where the product inside is waxy-like polymer.The internal part of the vessel is coated with 60-micron teflon. The intention is to avoid removing the teflon coating. Unfortunately, the waxy-like polymer is also difficult to remove without damaging the coating.Thus, is there any available NDT technique to do NDT inspection with these parameters in place (teflon+unknown thickness of polymer). The inspection to be conducted is to know the remaining thickness for internal vessel wall (remember the outside is jacketed) and to inspect the integrity of the internal wall's weldment.
: Any info would very much appreciated. Thanks.
------------ End Original Message ------------




    
 
 Reply 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
04:14 May-16-2005
Re: NDT for UT measurement and Crack Detection
Dear Friends,

I feel that UT is the best bet, assuming that the attentuation in the polymer layer is not too severe. Is there no solvent which helps in removing the polymer without damaging the teflon coating?

Swamy

----------- Start Original Message -----------
: I think we need to know a bit more about the thickness of this polymer - "unknown thickness" doesn't give us enough to draw any conclusions from.
: Are we talking microns (i.e comparable to the PTFE coating thickness) or significantly more.
: Any method / procedure will have a maximum allowable thickness, so you will need to equip yourself with a coating gauge to measure it and be prepared to remove some of the polymer if the thickness is excessive.
: Any of the main techniques discussed (UT, ET, ACFM) can 'probably' be applied through coatings of a milimeter or more, but as the coating thickness increases the results will become less reliable.
: For UT the propeties of the polymer material will also be important
: I think this discussion has progressed to the point where we need more specific information.
: Joe
: : : : Is there any available NDT technique to measure thickness and detect crack on weldment on carbon steel with PTFE coating (50-60 microns) on it? The intention is not to remove the coating to conduct the inspection. Advance thanks for the response.
: : : Can you give more detail? Can you access both sides of the part also what is the thickness of the part?
: : Thanks all for the feedback.
: : The mentioned equipment is a jacketed vessel where the product inside is waxy-like polymer.The internal part of the vessel is coated with 60-micron teflon. The intention is to avoid removing the teflon coating. Unfortunately, the waxy-like polymer is also difficult to remove without damaging the coating.Thus, is there any available NDT technique to do NDT inspection with these parameters in place (teflon+unknown thickness of polymer). The inspection to be conducted is to know the remaining thickness for internal vessel wall (remember the outside is jacketed) and to inspect the integrity of the internal wall's weldment.
: : Any info would very much appreciated. Thanks.
------------ End Original Message ------------




    
 
 Reply 
 

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