Quote Originally Posted by calweld View Post
I believe anytime you move a piece of metal back-and-forth thousands of times in close proximity to another piece of metal, you will end up with magentism.

Wow, this is an old thread, but it got brought up so here goes....

Oil field tubular goods don't become magnetic due to motion, they become magnetic by being in the earth for a period of time.
Bury any large, long metallic object in the earth (and pipelines are both large and very, very long. Drilling tubulars are lesser so but still qualify) for a period of time and they become magnetized by the earths magnetic field.

It's that simple.
Even severely magnetized pipe can be welded successfully to code standards.