Hey folks, what’s the best way to tackle this rot, also does anyone know the size of this pipe and where one would get it? Thanks guys

 

Not quite sure what we are looking at there but if just a straight steel tube with rot in the center, my fix would be cut out the rot and get a tube which will slide over(sleeve) that tube and weld it. Near me there is a store called Metal Supermarket which is kind of expensive but would have the tubing. Use a caliper to measure the Outside diameter of that tube and try to get one with slightly larger I.D.