X2, as long as the fitup is good and your welder is powerful enough.
I was thinking the same thing, the tubing will be the limiting factor. That being said, C looks to have the most welded surface.A gusset is cheap insurance. But I imagine any of those joints would hold just fine if it's welded good. You might have problems with the tube bending before the welds let go, would be an interesting test
Well my internet armchair quarter backing thinks that that tube as pointed out will be the weak point as others have said! That weld joint [C] could be strengthened by the two plates as Daniel proposed, then I would add a plate at a 45° angle inside touching the inside corner then plug weld generously along both the top and bottom tangent points. Then add a outside corner cap plate (inside or outside both with pro's and con's). With an opening and inside plates (inner and outer) you have sn excellent opportunity for great penetration at the apexes. I would do the outer course with an exterior cap with full wrap weld. Weld the inner 3 gussets together before insertion to make final welding the easiest. Harry [pic for general concept as words alone may have been lacking! LOL!]A gusset is cheap insurance. But I imagine any of those joints would hold just fine if it's welded good. You might have problems with the tube bending before the welds let go, would be an interesting test
what size rectangle tubing are you thinking about using? 1x2?)
