HW radiator PEX piping

I've read about PEX piping for all plumbing and the plumbers used this for our new material. I'm moving an old cast iron radiator and wondered if there is a PEX pipe approved for boiler water in this application. I'm in St. Paul MN, the house is a 1907, the radiator is only going from one side of a hall to the other and there is a circulating pump on the newer boiler. I'd prefer to use new threaded pipe for aesthetics but my experience with that is limited and don't know if I can arrange lengths accurately enough to make things fit. Is PEX OK for hot water radiators?