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- since 1996 -
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Technical Discussions
Randy Plis
Sales,
Metals Testing Company, USA, Joined Jun 2002, 9

Randy Plis

Sales,
Metals Testing Company,
USA,
Joined Jun 2002
9
14:16 Dec-27-2016
MPI & FPI Sequence

Has anyone ever done an experiment to confirm whether performing MPI before FPI negatively impacts the FPI performance?

    
 
 Reply 
 
George
NDT Inspector,
USA, Joined Dec 2016, 6

George

NDT Inspector,
USA,
Joined Dec 2016
6
12:37 Dec-28-2016
Re: MPI & FPI Sequence
In Reply to Randy Plis at 14:16 Dec-27-2016 (Opening).

Randy, this is an excellent question. If possible I choose to perform PT prior to. A thorough pre-cleaning (scrubbed clean to where it will pass a white glove inspection) is always critical before PT, especially if MT was done first.

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

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
13:53 Dec-28-2016
Re: MPI & FPI Sequence
In Reply to Randy Plis at 14:16 Dec-27-2016 (Opening).

No I have not tried this nor have I put the cart before the horse!

Preparation for PT aims to allow maximum penetrant ingress into open-to-surface voids. One of the most critical steps of a liquid penetrant inspection is the surface preparation. The surface must be free of oil, grease, water, or other contaminants that may prevent penetrant from entering flaws.

But if needs (or curiosity) must and you are not certifying that testing has been performed in accrdance with most specifications which stipulate PT before MPI AND a thorough surface cleaning is made then maybe test efficacy will not be significantly reduced. If you put your TAM panel trough this then you will get an idea.

Use of both MT and PT on the same item is rare but it is called for on testing chromed items but ALWAYS penetrant first.

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

Bojan Bencic

Engineering,
Turbomehanika d.o.o.,
Croatia,
Joined Nov 2014
8
19:34 Dec-29-2016
Re: MPI & FPI Sequence
In Reply to Randy Plis at 14:16 Dec-27-2016 (Opening).

It's all about cleaning before PT. There was a lot of reasearch done on this subject, here is a good start for you:
https://www.nde-ed.org/EducationResources/CommunityCollege/PenetrantTest/MethodsTech/researchoncleaning.htm
In short, if you have a choice, don't do MT before PT, it will probably have a negative impact on PT performance.

    
 
 Reply 
 
Randy Plis
Randy Plis
16:28 Jan-03-2017
Re: MPI & FPI Sequence
In Reply to Nigel Armstrong at 13:53 Dec-28-2016 .

Hi Nigel, Thanks for your response. You mention that most specifications stipulate PT before MPI. Could you provide a few examples of such specs? Thanks.

    
 
 Reply 
 
Randy Plis
Sales,
Metals Testing Company, USA, Joined Jun 2002, 9

Randy Plis

Sales,
Metals Testing Company,
USA,
Joined Jun 2002
9
16:38 Jan-03-2017
Re: MPI & FPI Sequence
In Reply to Bojan Bencic at 19:34 Dec-29-2016 .

Hello Bojan, Thanks for your reply. The link you provided does not appear to work. Could you forward the information, or provide an alternate link? Thanks again.

    
 
 Reply 
 
Bojan Bencic
Bojan Bencic
18:29 Jan-03-2017
Re: MPI & FPI Sequence
In Reply to Randy Plis at 16:38 Jan-03-2017 .

Download Cleaning

Sorry about that Randy, it was there last year, something happened.
Here is a pdf containing snapshot of the page as it appeared on 31 Dec 2016 01:06:29 GMT. Thanks to Google.
Hope it helps.
    
 
 Reply 
 
SharingNDT
Consultant, ASNT MT/PT Level 3, Quality Manager
SharingNDT, USA, Joined Jan 2017, 80

SharingNDT

Consultant, ASNT MT/PT Level 3, Quality Manager
SharingNDT,
USA,
Joined Jan 2017
80
18:27 Jan-13-2017
Re: MPI & FPI Sequence
In Reply to Randy Plis at 14:16 Dec-27-2016 (Opening).

Hi Randy,

I am unsure what specs dictates PT before MT. First, perform NDT in the sequence as described in the procedure, manual, or customer requirements.

If you read ASTM E1444 Appendix X1.1, it says," Some materials are far more suitable for magnetic particle testing than others. In some cases, liquid penetrant testing may be a more reliable testing method."

See? So you can perform PT after MT. There are procedures in every NDT specification for a thorough cleaning before inspection.

Do you need more help?

Peter Pelayo
ASNT Level 3 #177314
sharingndt@gmail.com

    
 
 Reply 
 
SharingNDT
Consultant, ASNT MT/PT Level 3, Quality Manager
SharingNDT, USA, Joined Jan 2017, 80

SharingNDT

Consultant, ASNT MT/PT Level 3, Quality Manager
SharingNDT,
USA,
Joined Jan 2017
80
20:20 Jan-13-2017
Re: MPI & FPI Sequence
In Reply to Bojan Bencic at 18:29 Jan-03-2017 .

This was a great reference.

Thanks!

    
 
 Reply 
 

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