I agree with Al, my lab has been extremely helpful in everything that I have done. Lots of tests I can take but ultimately I make the decision and they test it, I pay them lumps of money, LoL!
On the plate test if it's AWS D1.1 your asking about I believe the plates need to be 6" x 3" times two, 22.5 degree bevel, backing strip has a minimum or maximum width, I apologize I'm not sure of the spec, maybe 3" wide max? On mine I like the backing strip to extend past the plates an inch or so, run off strips. Weld it out 7018, root pass is wire brush or wire wheel only, I think I have seen some guys use a pick to get some slag out. With 1/8" rod, use 1/8" gap, a welding rod slipped into the gap before tacking works well. Oh, 3/8" plate for limited thickness, use 1" plate and that qualifies you unlimited in the position welded, i.e, 3g, 4g, etc.