I am currently setting up a test to qualify welders under this code. I am using A709 grade 36 1" plate. I need to use a backing strip for the test and I want to know whether or not I can use A36 material for the back up since it is identical to A709 grade 36. The reason I ask this is because I would have to order 2.5 tons of 1"x 3/8" bar in order to get it (due to mill order requirements). Any information would be appreciated.