Re: New to welding question.
I'm not sure. If cast iron, find a way to fasten that doesn't involve welding. If wrought iron, find a way to fasten that doesn't involve welding.
You have an antique there. A first timer welding to it will destroy its monetary & aesthetic value.
How do posts attach to the ground? are they hollow & sit on a steel post?
How do fence sections attach to posts. I presume screws?
I'm betting existing hinges bolt to the post & in turn to the gate. Fabricate new hinges that bolt in place if needed.
There are sure to be breaks somewhere. Were they repaired with weld?
An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.