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Technical Discussions
Theodoros Theodoulidis
Teacher, Researcher
University of Western Macedonia, Greece, Joined Dec 1999, 5

Theodoros Theodoulidis

Teacher, Researcher
University of Western Macedonia,
Greece,
Joined Dec 1999
5
09:10 Jun-20-2000
ID pit sizing

I am looking for updated information about sizing of ID pits with eddy currents in heat exchanger tubing.

I have seen a report referring to a reverse frequency mix of two frequencies. This is an artificial way of enhancing the 40 degrees angle between the wobble signal and the holes signal and is supposed to increase the above angle to 90 degrees. Does anyone know what exactly is reverse mix?

Thank you in advance



    
 
 Reply 
 
Richard D. Roberts
Engineering, Executive Managment
Quest Integrity Group, USA, Joined Nov 1998, 78

Richard D. Roberts

Engineering, Executive Managment
Quest Integrity Group,
USA,
Joined Nov 1998
78
00:52 Jun-24-2000
Re: ID pit sizing
gle to 90 degrees. Does anyone know what exactly is reverse mix?

: Thank you in advance




    
 
 Reply 
 
James Doyle
James Doyle
02:19 Jul-21-2000
Re: ID pit sizing
: I am looking for updated information about sizing of ID pits with eddy currents in heat exchanger tubing.

: I have seen a report referring to a reverse frequency mix of two frequencies. This is an artificial way of enhancing the 40 degrees angle between the wobble signal and the holes signal and is supposed to increase the above angle to 90 degrees. Does anyone know what exactly is reverse mix?

: Thank you in advance


Also see www.visualogic.com

Good luck,

Jim Doyle


    
 
 Reply 
 
John Hansen
Director, - Eddy Current Technology
ETher NDE Ltd, United Kingdom, Joined Oct 1999, 73

John Hansen

Director, - Eddy Current Technology
ETher NDE Ltd,
United Kingdom,
Joined Oct 1999
73
04:01 Aug-09-2000
Re: ID pit sizing
I guess a reverse mix is to take the data from two channels at different frequencies and then instead of removing an unwanted signal add together the siganl you want. How this is done to maintain sensititvity is a ggod question. You could double the height of the through hole and leave the wobble the same by for instance using two channels at the same frequency set the hole to 90 degrees in both, then conpletely attenuate the x axis on one and then add together both signals and then rotate the hole to 40 degrees.

You could also mix the wobble out in this way.

At the EPRI BOP conference in Scottsdale EPRI reported that the most reliable method they had found for depth sizing ID pitting was to use the max Y amp i.e. ignore wobble and phase.

Which if you think about it is much the same as the reverse mix.

Regards


John Hansen
Hocking NDT Ltd
: : I am looking for updated information about sizing of ID pits with eddy currents in heat exchanger tubing.

: : I have seen a report referring to a reverse frequency mix of two frequencies. This is an artificial way of enhancing the 40 degrees angle between the wobble signal and the holes signal and is supposed to increase the above angle to 90 degrees. Does anyone know what exactly is reverse mix?

: : Thank you in advance

:
: Also see www.visualogic.com

: Good luck,

: Jim Doyle




    
 
 Reply 
 

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