While 7018 is classed as an all position rod, It works best in flat and vertical down.
The term "Drag Rod" is correct, with the proper settings, in the flat position, you can strike a Arc and lay the rod on the metal, and it will run a bead all by itself.
Best "all around rod" I have ever used is 6011, it is a true all position rod, and very forgiving of less that perfect setup.
A great field repair rod.
To get back on topic, I am not sure what you are going to do about RFI from the welder, in reality, it is a huge spark-gap machine.
We use Plasma cutters at work to cutt stainless a lot, you should hear the hash and trash that they make.
Good Luck.
73
Jeff