John Howarth tested high voltages from a welder for us and reported..

I received the patches and rings for EMI durability testing yesterday. I tested them today in very close proximity (less than 10mm) to 200amp AC weld currents and HF start. Neither of which damaged the rings or patches. I also ran the HF start (a few kV ac) directly through the ring itself, which still works; so I'm most impressed

Awesome news :)