SANDblasting would be too coarse unless the blaster uses a finer grit and knows their stuff. But there's so many other blast media that it is not a problem. Talk to your blaster guy about what you have and what he's got. Once you show him how light the tubes are and what metal they are he'll know which media to use. Don't worry about your friend's opinion. They obviously think that the only sort of sandblasting out there is what is done on old bridges or to restore stone buildings.