On Saturday, April 8, 2017 at 11:02:21 AM UTC-7, christine wrote:
I am installing a 100 lb farm sink. The specs suggest supporting it for 300 lbs. I have...lengths of 12 gauge strut channel or .5 or .75 galvanized pipe.

Pipe is subject to buckling if used in compression, so a 2x4 would be better. The
prospect of rotation at joints means that pipe is rarely useful, and only with crossbracing
(like the turnbuckles on an old screen door). Nails and construction glue
will make a good ell in wood, but strut or pipe will require a gusset plate (or welding) to do
the same. I'd use wood.