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Technical Discussions
Sathiyaraj
Engineering,
TOSHIBA JSW POWER SYSTEMS PVT. LTD.,, India, Joined Apr 2013, 14

Sathiyaraj

Engineering,
TOSHIBA JSW POWER SYSTEMS PVT. LTD.,,
India,
Joined Apr 2013
14
05:38 Feb-19-2019
YOKE MPI Dry vs WET

Dear Friends,
In Yoke MPI DC Current
Compare Dry Particle vs Wet Particle
Which is most effective?

 
 Reply 
 
Rick Lopez
R & D,
John Deere - Moline Technology Innovation Center, USA, Joined Jul 2011, 191

Rick Lopez

R & D,
John Deere - Moline Technology Innovation Center,
USA,
Joined Jul 2011
191
16:13 Feb-19-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 05:38 Feb-19-2019 (Opening).

Your question is tough to answer, as you don't offer details on your application. In other words, "it depends".

For surface-breaking flaws, rectified current ("DC") and dry powder would not be ideal (AC current and wet fluorescent particles would be better option). Given your choice in magnetizing waveform, maybe you're hoping for some sub-surface sensitivity. Dry powder particles are larger in size, and past published studies have suggested that this feature makes them well-suited (possibly because of enhanced magnetic permeability) for sub-surface flaw detection (dry particles are better option).

 
 Reply 
 
Dent
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 252

Dent

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
252
16:39 Feb-19-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 05:38 Feb-19-2019 (Opening).

Dry particles are best used with AC due to increased particle mobility.

 
 Reply 
 
Keith Cain
NDT Inspector, ASNT Level 3
Chimaera Inspection Services, South Africa, Joined Jan 2009, 17

Keith Cain

NDT Inspector, ASNT Level 3
Chimaera Inspection Services,
South Africa,
Joined Jan 2009
17
06:10 Feb-21-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 05:38 Feb-19-2019 (Opening).

Hi Sathiyaraj

In determining which is the most effective particles to use with DC yokes, the following factors need to be taken into consideration:

- permeability of test material
- material thickness
- orientation of test surface i.e. vertical, horizontal, overhead etc.
- test surface condition i.e. as welded, ground, coated etc.
- field strength and direction
- positioning of yoke poles on test surface
- the distance between the poles
- type and orientation of discontinuities sought i.e. pre and in service
- surface or sub-surface discontinuities sought
- particle application technique
- particle size (often varies between manufacturers)

Experimenting with components that have known defects placed in different orientations will provide objectivity with the use of different particles.

Unless you have extensive experience in DC yoke use, it would be advisable to stick with the technique that you are most familiar with.

Greetings from South Africa.

 
 Reply 
 
P. Sathiyaraj
Engineering,
TOSHIBA JSW POWER SYSTEMS PVT. LTD.,, India, Joined Apr 2013, 14

P. Sathiyaraj

Engineering,
TOSHIBA JSW POWER SYSTEMS PVT. LTD.,,
India,
Joined Apr 2013
14
06:43 Feb-21-2019
Re: YOKE MPI Dry vs WET
In Reply to Dent at 16:39 Feb-19-2019 .

Dear Rick and Dent,

Thanks for reply

I did Yoke MPI with DC Current in the 10mm side drill hole Block - depth of the hole 1mm to 8mm

8mm Depth indication found in the Dry Powder

In the same condition when use wet fluorescent it detects up to 3mm only

compare to dry particles, wet Fluorescent particle have very fine microns

and mobility also high in the wet particles


Why this much difference between dry and wet particles in the same current

 
 Reply 
 
ASHOK KUMAR PATRA
,
Saudi K-KEM Engineering service co, Saudi Arabia, Joined May 2018, 55

ASHOK KUMAR PATRA

,
Saudi K-KEM Engineering service co,
Saudi Arabia,
Joined May 2018
55
10:46 Feb-21-2019
Re: YOKE MPI Dry vs WET
In Reply to P. Sathiyaraj at 06:43 Feb-21-2019 .

Dear Sathiyaraj ,


Sorry to say ,but can you please send me the video of 8 mm indication with dry DC yoke ,I just want to see. If it is ,it may be on flat surface what about vertical and overhead .

 
 Reply 
 
Sathiyaraj
Engineering,
TOSHIBA JSW POWER SYSTEMS PVT. LTD.,, India, Joined Apr 2013, 14

Sathiyaraj

Engineering,
TOSHIBA JSW POWER SYSTEMS PVT. LTD.,,
India,
Joined Apr 2013
14
12:37 Feb-25-2019
Re: YOKE MPI Dry vs WET
In Reply to ASHOK KUMAR PATRA at 10:46 Feb-21-2019 .

zoom image

8mm Depth Indicatoin

Dear Ashok Kumar Patra,

Please find the attached Image which was taken on the DC source with Dry Powder (Particle Size- 80 Microns) Downhand Position

8mm Depth indication found...

Same position I tried with wet fluorescent (Particle Size- 6 Microns) - Indication Not reveal

And Normally we'll not suggest Dry for Vertical and Overhead position - due to particle gravitational force it will not sensitive

Regards
Sathiya
 
 Reply 
 
ASHOK KUMAR PATRA
,
Saudi K-KEM Engineering service co, Saudi Arabia, Joined May 2018, 55

ASHOK KUMAR PATRA

,
Saudi K-KEM Engineering service co,
Saudi Arabia,
Joined May 2018
55
13:41 Feb-25-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 12:37 Feb-25-2019 .

THANKS IS IT HWDC OR DC. THANKS AGAIN FOR PICTURE.

 
 Reply 
 
Kumar
Kumar
02:13 Mar-06-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 12:37 Feb-25-2019 .

I m new to NDT, it's possible to find subsurface flaw by using DC yok.

 
 Reply 
 
Anmol Birring
Consultant,
Birring NDE Center, Inc., USA, Joined Aug 2011, 805

Anmol Birring

Consultant,
Birring NDE Center, Inc.,
USA,
Joined Aug 2011
805
07:12 Mar-07-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 05:38 Feb-19-2019 (Opening).

Classic question. See the response on Ketos ring for various combinations.

 
 Reply 
 
Sathiyaraj
Sathiyaraj
10:07 Mar-07-2019
Re: YOKE MPI Dry vs WET
In Reply to ASHOK KUMAR PATRA at 13:41 Feb-25-2019 .

Dear Ashok Kumar Patra,

Its DC Yoke...

Why this much difference between DRY MPI and WET Fluorescent MPI...

with respect to mobility, particle size, gravitational force wet method is most favour

Even though Dry acting major role in the sensitivity matter

How ?


Regards
Sathiyaraj

 
 Reply 
 
ASHOK KUMAR PATRA
,
Saudi K-KEM Engineering service co, Saudi Arabia, Joined May 2018, 55

ASHOK KUMAR PATRA

,
Saudi K-KEM Engineering service co,
Saudi Arabia,
Joined May 2018
55
05:46 Mar-09-2019
Re: YOKE MPI Dry vs WET
In Reply to Sathiyaraj at 10:07 Mar-07-2019 .

Dry powder is most favorable for AC and HWDC because these methods giving more mobility to iron powder by vibration , same in case of WET also.
DC and HWDC is good for subsurface discontinuity. but DC giving no mobility.
AC is only for surface discontinuity.

Try for different positions vertical horizontal and overhead , then you can say which is good for which positions.

And you can sure in which position you can test up to which depth.

 
 Reply 
 

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