I'm erecting a shade sail over a patio and planning to use 4"x4"x1/4" steel tubing on the four posts that will carry the fabric. The fabric will betensioned so that it barely flaps in anything but a very strong wind. I'm told there will be between 2000 & 3000 # pull at the connection points. The tube steel will be embedded in concrete 3' or more below grade depending on the height out of the ground. Two of the tubes will be 9' above grade and opposite from one another. Another will be at 10' above grade and the opposite one, the highest, at 11' above grade. Can anyone tell me if A500 B grade 4"x4"x1/4" tubing will do the job?