General rule for ships, at least heavily loaded ships, is to retire after some 60 or so years. There’s no exact number but it exists for each type of ship. Reason is material stress. Even though ship might look okay, they have a lot of stress when transporting cargo or in general dealing with waves. In time, these stresses cause material stress and eventually fracture.
This is the reason behind those videos on YouTube where ship splits in half in high waves. It’s not that ship can’t handle high waves, it’s simply that ship owner wanted to squeeze more money out of the vessel and didn’t want to retire it, even though he was most likely advised to do so.