Welding magnetic piping

[KyleBwelder]

Does anyone have any tips on how to weld a magnetized pipe. The tools used to monitor the piping has magnetized it. I cannot weld on the body of the pipe to connect them with a bar. The first bead would blow out until it finally got enough in between it to neutralize the magnetization. This unfortunately causes a huge mess which has to be ground off and it takes forever to do. So if anyone knows how to de-magnetize the pipe or anything to make welding it easier I would appreciate it.

 

[MagMike]

The only option I can think of is to wrap the magnetized pipe with a number of turns of heavy duty welders wire and run a decaying (down to zero), sinusoidal electric current through the wire. This should effectively demagnetize the pipe.

I hope the geometry of the pipe allows at least a few turns of wire.

 

[KyleBwelder]

Well it's a 12" pipe, I might have to try that, since I can't think of anything else to do. Thanks for the help.

 

[KyleBwelder]

I have tried something similar to this without success. If you could explain the specifics, (such as is AC current neccessary, how many wraps, with which lead,etc.) I would really appreciate it. Also, if anyone else would have any suggestions I would like to hear them, thanks.

 

[MagMike]

There are very few specifics in these instances, but here are some suggestions:
Wrap as many turns as you can on the outer diameter of the pipe.
Run as many amps of current as you can, without burning out the wire.
It doesn't matter which lead is positive/negative, you'll be magnetizing the pipe north/south multiple times, eventually bringing it down to zero.
You should use DC current, but you need to have a way to vary it and (most importantly) a way to reverse its polarity.
The current should reverse (and decrease in strength) every few seconds.

 

[hacksaw]

This query appears to be listed in the piping forum.

You might try use of a keeper to reduce the field in the gap. It works pretty good.