I appreciate you Shad, but I gotta interject.
Root pass depends on the schedule of your pipe, land thickness, gap, and preheat temp of your work. I won't ever run a root pass, (even 2") at less than 96 amps 1/8, or 135amps for 5/32 rod even on sch 40 2"
There are some companies that wont let you have more than 1/32 height on the inside of your root bead, (inside of the pipe). That means fast and HOT! With a capital H.....
If you are running too cold, you will stick the rod, or pile up on the inside. If you are running too hot, try a forward angle, (drag), and push in moderately to make the puddle chase your arc. If you are just plain too hot you will not be able to maintain coverage on the inside of the pipe and will have to come back and grind, start over on your root - or you will have a burn through on your hot pass, ) fish eye), which will fail on any xray.