In my non tradesman view, its a soak with penetrating oil 1 day, heat until cherry 20 minutes getting the torch ready and another 10 minutes heating, Hammering 5 minutes, repeat twice more for the other two segments.
1.) Cut the hinge off: 10 min with plasma including setup
2.) Weld the new hinge on: 10 min with mig welder including setup
3.) Paint: 15 minutes
4.) Trip to doctor after hauling welder around (1 morning)
5.) Beers on the aft deck under strict orders to take it easy (Priceless)