I am in the process of converting a couple of kegs to a boil kettle and HLT. I have cut the tops off and wanted to know if there is a proper cleaning procedure to follow in cleaning them up and prepairing them for use. I have heard of people doing several things like a simple cleaning with Barkeepers Friend, boiling a full keg of water and white vinager, and boiling a keg full of water and Oxyclean then letting it sit over night and scrubbing. The kegs are a little dirty but they are not really encrusted with gunk. Do I need to go hardcore on these guys? Will this 'beerstone' stuff cause me problems down the road if I dont get it all out now? What have you done? Any advice would be great.