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- since 1996 -

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Technical Discussions
aldo
Engineering
Italy, Joined Jan 2009, 39

aldo

Engineering
Italy,
Joined Jan 2009
39
15:25 Nov-13-2009
penetrant liquid on anodized alluminium surface

Hy all...
I have some questions above FPI on anodized alluminium surface..
I usually do not the FPI on this surface because the same surface is very porous and this causes a enormous background fluorescence that wolud be reduce contrast or mask possibility defect. So
1) I have read on specific textbook that is possile to do FPI on this surface but only method "C" (solvent removable).. Is it right?
2) During process anodized alluminium there is a phase that consist in sealing of this pourus by hydration Al2O3...Is possible to do FPI after process because i have not a porous surface and background fluorescence?

    
 
 
Jim Draper
Consultant, ASNT Level III MT PT RT VT
Draper NDT, USA, Joined Jul 2009, 99

Jim Draper

Consultant, ASNT Level III MT PT RT VT
Draper NDT,
USA,
Joined Jul 2009
99
19:37 Nov-13-2009
Re: penetrant liquid on anodized alluminium surface
In Reply to aldo at 15:25 Nov-13-2009 (Opening).

Aldo,
I'm not sure on this one, but it seems to me, after the aluminum has been anodized it would be to porous no matter what method is used. Also, after the anodized aluminum has been sealed, the penetrant would not be able to enter any defects.

    
 
 
Bill
Bill
21:22 Nov-13-2009
Re: penetrant liquid on anodized alluminium surface
In Reply to aldo at 15:25 Nov-13-2009 (Opening).

Aldo,
My experience with anodized aluminum is that the anodize is a conversion coating that basically changes the surface properties of the metal. The quality of this layer does not reflect to quality of the underlying material and testing it is not providing a evaluation of the part. Penetrant testing should be done on new parts prior to anodize but if the inspection is for service related defects such as stress cracks on parts that have been in the field, I would recomend using a fluorescent, post emulsified system, you can increase the emulsification time through expermentation until the background fluorescence is low enough to provide a good inspection. Method C would be the wrong way to go, unless you can strip off the anodize.

    
 
 
Michel Couture
NDT Inspector,
consultant, Canada, Joined Sep 2006, 834

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
834
23:11 Nov-13-2009
Re: penetrant liquid on anodized alluminium surface
In Reply to Bill at 21:22 Nov-13-2009 .

Gentlemen,

From past experience I can say that Method D and C can be done on Anodized Aluminium. Background is terrible and you got to live with it. It is one of those situation where the inspector must be extra vigilant not to miss any indications. For your info, all aluminium parts involved in making an aircraft are anodized and FPI is carried out after anodizing as per manufacturer's procedure.

The reason being is that when anodizing, you are actually removing a very thin layer of material by first dipping it in a mixture of Sulfuric and Hydrochloric Acid bath and then replacing it with a layer of chemical that will provide the protective coating.

Since acid is involved, the acid bath will expose any defect that may have been closed to the surface during the extruding process for exemple.

Removal of the coating is not recommended, because you are braking the protective bond and the aluminium will fall victim to its environment. If for any reason the anodize coating was remove, two solutions are at hand. One is to re-anodize the part or the second if allowed by the customer to apply a new coating through the Alodine process.

    
 
 
Jim Draper
Consultant, ASNT Level III MT PT RT VT
Draper NDT, USA, Joined Jul 2009, 99

Jim Draper

Consultant, ASNT Level III MT PT RT VT
Draper NDT,
USA,
Joined Jul 2009
99
13:49 Nov-24-2009
Re: penetrant liquid on anodized alluminium surface
In Reply to Michel Couture at 23:11 Nov-13-2009 .

A lot of the procedures that I see specify to perform liquid penetrant testing per ASTM E 1417. If that is what you have to go by, paragraph 6.8.2 reads, "The penetrant examination shall precede any surface finish, such as anodize, except for in service parts that may be examined without removing the anodize." I hope this will help.

    
 
 
Michel Couture
NDT Inspector,
consultant, Canada, Joined Sep 2006, 834

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
834
17:49 Nov-24-2009
Re: penetrant liquid on anodized alluminium surface
In Reply to Jim Draper at 13:49 Nov-24-2009 .

Jim,

You are totally right and this is what makes it a little more difficult. The anodizing does "suck up" the penetrant and no matter how much washing you do it still there. So many inspectors will have a tendancy to over wash. This is why with aluminium parts in the aircraft industry one has to be very diligent.

    
 
 
aldo
Engineering
Italy, Joined Jan 2009, 39

aldo

Engineering
Italy,
Joined Jan 2009
39
07:58 Nov-27-2009
Re: penetrant liquid on anodized alluminium surface
In Reply to Michel Couture at 17:49 Nov-24-2009 .

Tanks for your answers and you are been very clear and tanks for your professional opinions...
Best regards and Merry Christmas
Aldo

    
 
 
Theo Micottis
Italy, Joined May 2013, 76

Theo Micottis

Italy,
Joined May 2013
76
14:47 Mar-11-2016
Re: penetrant liquid on anodized alluminium surface
In Reply to aldo at 07:58 Nov-27-2009 .

Dear all, I'm facing the same situation in a factory. I have to witness a PT on welds of an aluminium structure in anodizing conditions. As the acceptability is 2mm for linear discontinuities ,I think that PT test is hardly applicable.
From Michael's post, I could read that on aircarft parts ,made of anodizing aluminium, it could be done. I don't know which is the acceptance level for aircarft parts, anyway I think that the overall test procedure is quite strict , that is easier to apply in aircraft factory than apply it in an assembly shop.
From your experience, which is the minimum indication clearly visible and assessable as non relevant indication or discontinuity in the anodizing conditions?
Regards Theo Micottis

    
 
 
Theo Micottis
Italy, Joined May 2013, 76

Theo Micottis

Italy,
Joined May 2013
76
06:05 Mar-15-2016
Re: penetrant liquid on anodized alluminium surface
In Reply to Theo Micottis at 14:47 Mar-11-2016 .

Any suggestion on this matter?No one faced the same issue? Regards Theo Micottis

    
 
 
Mike
Netherlands, Joined Dec 2013, 1

Mike

Netherlands,
Joined Dec 2013
1
18:43 Mar-17-2016
Re: penetrant liquid on anodized alluminium surface
In Reply to Theo Micottis at 06:05 Mar-15-2016 .

Hi Theo, i'm a ndt inspector at A surface treatment factory (Aerospace). All our producs (new, boeiing, airbus,lockheed martin, fokker etc.) are inspected before they get anodized. Maybe when it's not watersealed it's possible. For myself this is an interesting question. I think it's possible indeed, regarding the backglow. Like to read more About this matter.

Best regards,

Mike van Hek,
The Netherlands

    
 
 
R.
R.
15:27 Jun-20-2017
Re: penetrant liquid on anodized alluminium surface
In Reply to Mike at 18:43 Mar-17-2016 .

Hi all,

I have some questions about remove penetrant liquid (pink area) form anodized alluminium surfaces.
After NDI, inspector didnt remove all penetrant from anodize surface. Recommended NDI cleaner doesnt work. I have a few pink area on material. What is the best way to remove penetrant with out grinding surface?

Thanks for help

    
 
 
Peter P.
Consultant, ASNT MT/PT Level 3, Quality Manager
SharingNDT, USA, Joined Jan 2017, 79

Peter P.

Consultant, ASNT MT/PT Level 3, Quality Manager
SharingNDT,
USA,
Joined Jan 2017
79
21:02 Jun-20-2017
Re: penetrant liquid on anodized alluminium surface
In Reply to aldo at 15:25 Nov-13-2009 (Opening).

1. Solvent removeable will only increase the amount of background because the penetrant is going to be absorbed and spread more than dry developer.

2. You can increase emulsification time to decrease background but you run the risk of missing shallow discontinuities, therefore, use a filtered particle penetrant.

    
 
 

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