T post gate hinges
T posts are a popular, low cost fence post option. They're lightweight, strong, and usually painted, so you don't have to worry about finishing them. They are usually knocked or pounded into the ground rather than being installed in concrete, and they're popular for agricultural fence systems.
Typically, T posts are not used as gate posts, because they can't take as much weight as a steel fence post, and because they're usually not installed in concrete, they don't have the counter balance weight to handle a gate that opens and closes frequently.
However, if you do need to hang a small, lightweight gate that won't be used very often on a T post, there are T post gate hinges designed for the job.
T post gate hinges slip over the T post and are held in place by the weight of the gate itself. They have a gate hinge pin that acts as the male part of the gate hinge assembly, and fits into the corresponding loop or female part of the hinge assembly, which is usually a bolt on gate frame hinge on the gate itself.
Buy a T post gate hinge on Amazon