Modern fridges are an interesting example. Most of the "active" parts and fittings are repairable with effort, even if manuals and parts are not easy to get.

Modern fridges are an interesting example. Most of the "active" parts and fittings are repairable with effort, even if manuals and parts are not easy to get. However in all modern fridges I have looked at, the structure is folded sheet metal which is not designed to be taken apart. Certain key panels cannot be opened out without distortion that will affect the fit. Inside the voids there is polystyrene (or similar) insulation. Eventually that insulation gets stinky and moldy and that is pretty much the end of the fridge because the insulation is inaccessible and cannot be replaced. You can try hitting it through vents, with bleach, but you cannot get it back to "as new". This kind of non-mechanical failure eventually renders the fridge un-usable for food. It seems like it would take an entirely different design to anything I have seen on the market to create a true "50 year fridge".