Hi Brian,

I'd say yes. I assume you're running this by the EOR for approval. He may require that the formed plate meet the minimum yield and tensile properties of manufactured tubing unless the design loads can support less. The most common grade in the structural field is ASTM A500 Grade B, which has a minimum yield of 46 ksi and a minimum tensile of 58 ksi. We had an odd sized 16" x 12" tube on a job once. The detailer failed to put it on the mill reservation list, so the first time I knew it existed was when I was reviewing the approval drawings. Since this was a fast track job, we couldn't get into a mill rolling in time to make delivery, and we couldn't find it at a warehouse. The engineer approved A36 bent plates with full penetration welds, but we had to increase the plate thickness from 5/16" to 1/2".
Whoever does the plate forming should make sure that the bend lines are transverse to the direction of rolling, if possible, and that the minimum radius for cold bending is not reduced. Should you use A36 plate, the minimum radius for thicknesses of up to 1/2" is 1.5 times the thickness, and 1/2" to 1" thick is 2 times the thickness. If it is not practical to bend with the grain, the minimum radii can be doubled. Just a couple things to consider.