Can I MIG weld a threaded galvanized steel pipe to a galvanized malleable fitting?

This is not a plumbing project, but I am building a small 1/2" pipe ladder for a dock (only 2 rungs). Most of the fittings will be threaded together, but by design, the joints of the upper ladder rung cannot be twisted together. I have ground down both the male and female threads, so the pipe slips into the fitting. It would be nice to run a weld on this (although, the rung is very tight and not going to have any structural benefit to the ladder). Another idea is just to epoxy the joint to help seal it and possibly keep water out.

Thanks for any info.