I have done pipes that where not quite that bad and freezing helped. The biggest thing about freezing is to get it capped off real well and fill as full as you can with water. This is an old trick I have been doing on motorcycles gas tanks for 35 plus year. Now you do have to make sure you do not bust the pipe or tank and do it while you are at home to keep and eye on it. I some times have to repeat the process.