I'm finally getting my structural cert, and I had a few questions before I dove off into the deep all by me onesies. I'm doing the unlimited thickness on 1" plate. Vertical up, 1/4" root with 1/4" backing plate and 60 deg bevel, 8" long.

I'm worried about warping. Do they care, or should I make an effort the jig the pieces to keep them from shrinking toward the weld?

Should I preheat the plates, or are they just mostly looking for clean welds on the inside? I'm going to weld, grind to shiny, weld, grind, etc.

I've never done a weld with a backing plate or a root quite that wide. Should I make one big sweeper root, or run one for each plate, concentrating on the backing?

Lastly, are sweepers better all the way out, or should I stack my beads?

I figure a lot of you guys have done this, and maybe there are some radiographers amongst you.  Any other pointers I might need would be great, also.  The plates cost me quite a bit, so I only want to do this once.  Thanks for the info.