I'm assembling my kegerator now and am thru most of the hard stuff. Want to run my beer lines thru some copper tubing. The tubing is already attached to the tower. My question is how do I get the tubing thru the copper pipes. Either disconnect at the tower but would need to get a new wrench or can these fitting at the end of the tubing come off so i can slip the copper pipe over this end. They seen pretty secure.