I'm doing a kegerator conversion and would like to put in a couple of gas lines for an external tank with a double regulator. (That would allow me to have two different pressures for initial carbonating and serving.) The gas lines are 9/16 OD. I'm leery of just pushing them through a 9/16 hole as the ragged edges may score the gas lines. So, I'd like to use bushings or grommets. The refrigerator wall is about 1 1/2 inch. Do I really need bushings? If so, I'm having a hard time finding what I need. Has anyone else done this and if so, do they have part numbers? Thanks for any help.