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2878 views
05:20 Mar-03-2009

Engkus Kusnadi

NDT Inspector, -
PT SEAMLESS PIPE INDONESIA JAYA,
Indonesia,
Joined Apr 2007
5
Magnetic field of Circular magnetization

Dear All

Why magnetic field of Circular magnetization by shootin rod weak and take time appears on Burmah Castrol
Stip than Longitudinal Magnetization by Coil.

Regards,

Kusnadie

 
07:38 Mar-05-2009
mandar
Re: Magnetic field of Circular magnetization In Reply to Engkus Kusnadi at 05:20 Mar-03-2009 (Opening).

Dear kusnadie ,

your question is not clear to me as magnetization by central conductor and by coil are two entirely different magnetic fields please give more information about part geometry and methods of magnetization used

 
01:00 Mar-06-2009
Kusnadie
Re: Magnetic field of Circular magnetization In Reply to mandar at 07:38 Mar-05-2009 .

Dear Mandar,

Thank you,
During conduct inspection on seamless pipe by Wet Magnetic Particle Inspection i use Burmah castrol strip to check sufficiency of magnetic field. First time the pipe magnetize by shooting rod to produce circular magnetization then verify sufficiency of magnetic field by Burmah Castrol Strip but indication get weak and take time to appears than longitudinal field by coil on 2nd step. Whereas all facility already on good condition and calculation Formulas
as per ASTM.

Regards,

Kusnadie

 
15:28 Mar-09-2009

Andreas

NDT Inspector, Specially in the oilfield
Tuboscope Vetco(Deutschland)Gmbh,
Germany,
Joined Oct 1999
126
Re: Magnetic field of Circular magnetization In Reply to Engkus Kusnadi at 05:20 Mar-03-2009 (Opening).

The formula you refering to is for longitutinal mag not for circular.Have a look into the ASTM E-709.
There are also some "rules of thumb" if not specified by the specification you working to.
For direct cirular mag use 300 - 800 amps per inch diameter when using a central conductor.
By using a prod use use 90 - 115 amps per inch prod spacing for parts up to 3/4" thickness.For thicker parts use 100- 120 amps per inch spacing.
This are only estimates better to verify the field my measurement.


regards

andreas

 
20:32 Jul-07-2010
Tim Brown
Re: Magnetic field of Circular magnetization In Reply to Andreas at 15:28 Mar-09-2009 .

The circular field that is created with the central shooting rod doesn't leak much from the pipe, especially if the surface condition is good. By comparison, the longitudinal field created in the pipe by the encircling coil will have a very strong leakage field that can easily be detected with a simple field indicator.

The use of Burmah Castrol strips to verify the strength of a residual circular field in a pipe is questionable and not reliable.

 
21:51 Jul-07-2010

Andreas

NDT Inspector, Specially in the oilfield
Tuboscope Vetco(Deutschland)Gmbh,
Germany,
Joined Oct 1999
126
Re: Magnetic field of Circular magnetization In Reply to Tim Brown at 20:32 Jul-07-2010 .

Hallo Tim ,
when you have circular field there will nearly no flux leakage at the surface. To prove the field with the strip ,you need to find a dent etc at the surface and place the strip there.
You will see than that the strip works.

Andreas

 
00:58 Jul-08-2010

Jim Draper

Consultant, ASNT Level III MT PT RT VT
Draper NDT,
USA,
Joined Jul 2009
99
Re: Magnetic field of Circular magnetization In Reply to Andreas at 21:51 Jul-07-2010 .

I like to use QQIs or a hall effect gauss meter to verify the strength of the circular field. Formulas do not take into account the permeability of the material. Another thing I have done is, use a scribe to scratch a line running parallel with the part. This should show that you have established a circular field. It also takes more amps to produce a sufficient shot using contacts than is does when using a coil.

 


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