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Technical Discussions
Michael Williams
,
United Kingdom, Joined Nov 2016, 9

Michael Williams

,
United Kingdom,
Joined Nov 2016
9
14:56 Nov-03-2016
MPI White contrast alternative

Hi,
Hoping someone can help. I work for a fabrication company and we use MPI quite regular. The problem is cleaning the paint of the weld sometimes holds the job up quite a bit (they don't like us to use acetone that much). I've been looking into alternatives like Fluorescent MPI. The problem is because its essentially a large open space that we work in, working in the dark isn't really an option. Is there an MPI method, like Flourescent that can be done in lighter conditions?
Thanks
Mike

    
 
 Reply 
 
Bojan Bencic
Engineering,
Turbomehanika d.o.o., Croatia, Joined Nov 2014, 8

Bojan Bencic

Engineering,
Turbomehanika d.o.o.,
Croatia,
Joined Nov 2014
8
16:13 Nov-03-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 14:56 Nov-03-2016 (Opening).

Fluorescent particles will not work well in light conditions, as you already know.
White paint is only used to increase contrast with mainly black particles.
You can get particles in other colors (red, yellow...) that could have stronger contrast with your base material (provide better visibility of indications on background). Then you might not need white paint at all. Best way is to try it yourself.
Of course, it also depends on the standards that you work by and customer approval.

Best regards,

Bojan

    
 
 Reply 
 
Michael Williams
,
United Kingdom, Joined Nov 2016, 9

Michael Williams

,
United Kingdom,
Joined Nov 2016
9
16:16 Nov-03-2016
Re: MPI White contrast alternative
In Reply to Bojan Bencic at 16:13 Nov-03-2016 .

Hi Bojan,
Thanks for the reply, but the colour of paint isnt the issue. Its the fact it has to be fully removed, which can take hrs with a wire brush.
Regards
Mike

    
 
 Reply 
 
Bojan Bencic
Engineering,
Turbomehanika d.o.o., Croatia, Joined Nov 2014, 8

Bojan Bencic

Engineering,
Turbomehanika d.o.o.,
Croatia,
Joined Nov 2014
8
16:48 Nov-03-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 16:16 Nov-03-2016 .

Hi Mike,
I thought you were asking about cleaning up after the MPI using background paint and visible particles.
If you are asking about pre-cleaning the parts (before MPI), fluorescent MPI would require more pre-cleaning than visible particles. Sorry.
Regards,
Bojan

    
 
 Reply 
 
Edinaldo de Lima Silva
Other, Operational MAnager
JBS Inspeção e Ensaios Ltda., Brazil, Joined Sep 2016, 3

Edinaldo de Lima Silva

Other, Operational MAnager
JBS Inspeção e Ensaios Ltda.,
Brazil,
Joined Sep 2016
3
17:07 Nov-03-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 14:56 Nov-03-2016 (Opening).

Michael Williams good afternoon.

One time I had to do a test in a condition like that, I have used a Plastic Film, one of that you put food at the refrigerator.
First of all I had make tests in a Circular Padron, I put the film after, I coat that with Contrast paint, and measure the depth of coating, Its almost 50 microns.
How that was only a test to see if it show possible we did without a procedure.
But when you take out the film, you have the surface, in perfect condition.
It haven't shows so easy to work because the film is so soft and fragile, but it was a way.

Remember that was Just a test.

    
 
 Reply 
 
Michael Williams
,
United Kingdom, Joined Nov 2016, 9

Michael Williams

,
United Kingdom,
Joined Nov 2016
9
17:19 Nov-03-2016
Re: MPI White contrast alternative
In Reply to Edinaldo de Lima Silva at 17:07 Nov-03-2016 .

Hi Edinaldo
Thanks for the info. So you put a film over the weld, then sprayed the paint over the film and tested through that?
Regards
Mike

    
 
 Reply 
 
Gerald Reams
Engineering,
Industry, USA, Joined Aug 2012, 180

Gerald Reams

Engineering,
Industry,
USA,
Joined Aug 2012
180
18:22 Nov-03-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 17:19 Nov-03-2016 .

What is the white paint's use? Is it an existing, painted weld? are you painting the area white for a contrasting background?

If you only want a white contrasting background, I suggest that instead of white paint, use white nonaqueous aerosol spray developer. This is used in liquid penetrant examination. a thin coat will provider a nice contrasting background that is removable by brushing.

Gerald Reams,
Level III

    
 
 Reply 
 
Leo
NDT Inspector,
Norway, Joined May 2008, 104

Leo

NDT Inspector,
Norway,
Joined May 2008
104
03:24 Nov-04-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 14:56 Nov-03-2016 (Opening).

In the most of the cases fulfilling specifosations takes time and when one is cutting corners requirements are not met.

Personally dont think a use of penetrant developer as background, as suggested above, would work out since the flow of mag suspension will likely wash it away.

You could try blue light source with dual purpose mag suspension and yellow glasses and some kind of umbrella to darken the surface. I havent tried Blue light myself but have heared of them.

Probably the best option, as already suggested, is to find a mag particle colour, that gives the best contrast without white background.

    
 
 Reply 
 
Michael Williams
,
United Kingdom, Joined Nov 2016, 9

Michael Williams

,
United Kingdom,
Joined Nov 2016
9
08:31 Nov-04-2016
Re: MPI White contrast alternative
In Reply to Leo at 03:24 Nov-04-2016 .

Thanks for the replies,
I thought Bojan Bencic was recommending a different contrast color, not a different particle color. I'll look into that I think.
Regards
Mike

    
 
 Reply 
 
Paul Skidmore
USA, Joined May 2012, 28

Paul Skidmore

USA,
Joined May 2012
28
12:38 Nov-04-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 14:56 Nov-03-2016 (Opening).

Use a black out curtains that you can buy

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

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
13:15 Nov-04-2016
Re: MPI White contrast alternative
In Reply to Paul Skidmore at 12:38 Nov-04-2016 .

Some MPI consumable manufacturers market special WCP termed 'strippable' though while such paint may be readily strippable on a flat smooth surface usually it is not so easily removed from rough surfaces, weld toes and cap ripples.

    
 
 Reply 
 
SHANKAR ARUMUGAM
Other, NDE Engineer
India, Joined Oct 2013, 39

SHANKAR ARUMUGAM

Other, NDE Engineer
India,
Joined Oct 2013
39
14:16 Nov-04-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 14:56 Nov-03-2016 (Opening).

As Mr.Bojan Bencic said you can try other different color particles which suits to your background area.

Also now some white contrast paints are coming with improved formula with respect to the easy post cleaning ability. No need to use cleaners. You can try it.

Regards,
Shankar

    
 
 Reply 
 
P V SASTRY
R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D, India, Joined Jan 2003, 195

P V SASTRY

R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D,
India,
Joined Jan 2003
195
05:05 Nov-07-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 14:56 Nov-03-2016 (Opening).


Fluorescent Magnetic particle testing does not necessarily require dark spaces. If your black light is powerful ( it should meet the specified intensity requirements) the testing can be done inside a shed where the the sun light does not directly come in.

If some body is skeptical they can try any no. of artificial or natural defects under these conditions using a no. of operators to remove subjectivity.

Good luck

P V SASTRY

    
 
 Reply 
 
Michael Williams
,
United Kingdom, Joined Nov 2016, 9

Michael Williams

,
United Kingdom,
Joined Nov 2016
9
08:43 Nov-07-2016
Re: MPI White contrast alternative
In Reply to P V SASTRY at 05:05 Nov-07-2016 .

Hi
I got an email recommending dry particle inspection, using coloured particles such as yellow (https://www.nde-ed.org/EducationResources/CommunityCollege/MagParticle/TestingPractices/Dry%20Particle.htm). Has anybody used this? And if so are they're any downsides?
Thanks
Mike

    
 
 Reply 
 
Conor Douglas
Conor Douglas
10:41 Nov-07-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 08:43 Nov-07-2016 .

Hi Micheal,

Have you thought about doing Eddy Current (ET). No paint required and will still find surface breaking defects.

Where is your company based? I could supply an ET technician within the UK until someone in your company, possibly you, meets the training hours required to sit an ET exam.

My email is on the comment, please do get in touch.

Thanks

Conor

    
 
 Reply 
 
P V SASTRY
R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D, India, Joined Jan 2003, 195

P V SASTRY

R & D, NDT tecniques metallurgy
TAKEN VRS FROM THE POSITION OF SR. DEPUTY GENERAL MANAGER BHEL CORPORATE R&D,
India,
Joined Jan 2003
195
12:34 Nov-07-2016
Re: MPI White contrast alternative
In Reply to Michael Williams at 08:43 Nov-07-2016 .


You can very well use dry color powder. But there are some practical difficulties.

For getting adequate and uniform coverage you have to spend more time for spraying the particles. If the powder is thickly spread interpretation problems will arise again slowing down the inspection. It is another riddle when the particles accumulate in the undercuts and weld ripples.

For getting uniform and quick coverage you need to use a powder blower.
When I have last used the powder blower (35 years back) made by Magnaflux it was quite bulky requiring electrical connection and some cleaning/ maintenance problems were there.
I do not know the presently available blowers. (Some time back I made a small hand held battery operated dry powder blower on somebody's specific request. I do not fancy this myself.)

On the other hand the fluorescent particle mixed in kerosene ( you can also use water based-mixing facilitated by a water conditioner) medium are the easiest way of spraying on to the job and practically you get very good sensitivity with one of the highest inspection speeds.

you do not need exactly dark rooms for conducting this test. Shaded areas of the industrial sheds are enough but the black light should have the specified intensity. I have been using this technique for more than 40 years and continuing now also. However it is important to use Fluorescent particles from a standard and renowned supplier like Magnaflux etc.

Good luck

P V SASTRY

    
 
 Reply 
 

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