My 6 gallon compressor just isn't getting the job done. I think I want to just get a bigger tank and connect it with the old one. I can get an old 15 gallon beer keg for $10, might I be able to use that as an air tank? Does anybody know how much pressure there normally is in a keg? Are there any standard size threaded fittings on the keg? I would like to avoid welding it...