This is a common problem that occurs when lengths of pipe crash together during the shipping process. Magnetism results in arc blow, this occurs during current welding. This often can be severe and can cause weld defects that will need to be repaired.
If your metal gets magnetised there’s a few options you can take. The first thing you can do is remove the magnetism completely, however this would require expensive equipment. Or, you could determine the extent of the magnetic pull with a gauss gauge before you place a demagnetiser coil around the pipe.
A common method of Demagnetising, is to create a magnetic coil with the work lead. By wrapping the lead around the pipe, and then using a current (in the lower range of what is suggested) deposit a root pass with a short arc length based on the size and type of the electrode.
Since the Arc Blow occurs during DC welding, try switching to alternating current to deposit the initial weld bead. Finally, switch back to DC for the remainder.
During all Demagnetising processes, be sure to pay close attention to the weld puddle, maintain a short arc length, and remove all deposits after each bead.
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