My pool top railings are peeling. I can't replace them. Can I scrape them and put a sealer of some kind on them?

Your railing is likely stell or aluminium. You should test with a magnet and if it sticks use a good exterior epoxy paint made for metal. If the magnet does not stick use an epoxy that says it works on aluminium. Rust-o-leum makes both. http://www.rustoleum.com/zinsserhp.asp