I've been building a working corral and loading chute, and as part of that project I purchased some used gates off craigslist. They're heavy steel gates with interesting hinges. Here's a couple of them. This particular hinge was designed to mount on the corner of a square post.
On the gate side there's a pipe of just the right diameter to fit inside the hinge. On that pipe there's a little piece of the larger pipe (where my finger is in the photo above) to act as a stop.
Here's a version of this hinge on the gate, but for mounting on the flat face of a beam. these gates are at least 45 years old. they're made from heavy steel pipe. A 16' gate (most of them were 16') weighs about 250lbs.
I liked these hinges so much that I decided to make 8 or 10 of them to replace the standard gate hinges. here I'm using a big pipe cutter to cut the tub into the right size.
I'll then either weld flat plates to these small pipe segments, or angle-iron for corner mounting. takes maybe 5 minutes per hinge to cut the pipe, clamp and weld it, and then drill the mounting holes. I'm going to add grease fittings to these so that I can grease the hinges as needed. Since the old hinges lasted most of 50 years already, I think that these will outlive me.