I asked the question too early and without considering well: is a matter for the calculation of square tubing to build the figure, is a question that I was asked but I think that the calculation of the other figures is not correct. I think the request is just to know the total length of pipe required.
So in the example top/left the length is: 1160+1050+750 = 3000
@roy_043 > Why isn't the max. length of A: 3000+1000+250+1200+1100=6550?
maybe this is the exact calculation A: 3000+1000+500+1200+1100=6800
Now ask other explanations.