So for senior design we are going to be tensioning some wires between two poles. The poles are going to be 3" pipe and will be anchored on the bottom. At 5' and 8' above the ground we are going to have horizontal members welded to the vertical tube. These horizontal members are going to be about 1' long on each side of the vertical tube and we will be pulling on the ends of these. We were thinking of using a 3" pipe on each side, welded to the vertical piece, to create these horizontal members. Will the welds hold a 400+ pound load about 1' away?
Alternatively, what are some other designs that might work better? What if we used a smaller pipe dia.? Would it still hold?