And the conduit is this, probably 2" but other sizes are available:

The hangers look like this:

The conduit was relatively tick and may be OK for outdoor use. The hangers seemed thin and not galvanized/zinc plated to prevent rust.
What's a good resource to find these types of things? The mast will be attached to a vertical steel beam on the roof of an office building. We would either drill holes and tap into the beam or use metal strapping.