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Re: [MW:4130] Demagnetization after completion of MPI test

By Materials & Welding
Dear Mr. Raghavendra
 
1.  Carrying out the MT using AC yoke will not necessaite demagnatization.
2.  When DC is used, you may reverse the current flow and progressively decrease the magnetic current. If you have done the MT using 900 amps. you must do the same with initial current of 900+ and decreasing.
3.  Carry out the MT on completion of all welding just prior to PWHT.  If MT is required after PWHT carry out the same using AC yoke.
 
Regards
 
Gopu Nair


--- On Thu, 21/1/10, PEMMARAJU RAGHAVENDRA <rpe@hzw.ltindia.com> wrote:

From: PEMMARAJU RAGHAVENDRA <rpe@hzw.ltindia.com>
Subject: [MW:4123] Demagnetization after completion of MPI test
To: materials-welding@googlegroups.com
Date: Thursday, 21 January, 2010, 5:54 PM

Dear All,

Can any one tell us the various methods / procedure  of demagnetizing the weld after completion of Magnetic particle testing on Ferritic steel welds.

Regards,

Raghavendra 

Larsen & Toubro Limited
www.larsentoubro.com

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