I need to attach a metal flange to concrete. It is used in a horse barn, It will be welded to a cross beam at the top and have three rails attached to it. Would the Gorilla glue work. I can also weld a rebar to flange and drill down into concrete to eliminate side to side movement.

My concern with using Gorilla Glue with this application is that whenever you glue two different surfaces together (Metal and concrete), they will expand and contract at different rates when exposed to temperature variations and this will put some extreme stress on your glue line.  Another issue in utilizing Gorilla Glue for this application is the difficulty in proper clamping pressure while the glue is curing.  Good clmaping is very important to maximize Gorilla Glue performance.

I suggest considering Gorilla Epoxy as a possible alternative, although again, I worry about the expansion and contraction rates of the two substrates.  The epoxy will still need to be clamped - but clamping force requirements are less critical and handling time is a bit faster (90 minutes vs 1-2 hours for Gorilla Glue).

Mary-Ellen