I use Sanke kegs for fermentation and serving too. First cleaning I pull the spear and empty it then heat water in the sanke to boiling at 1/4 full I add oxyclean and use a carboy brush connected to an extension to scrub the insides. I then let it sit 20 minutes and scrub again. I then fill to half full and scrub again. I then siphon all the cleaner into buckets and rinse the keg upside down and inspect with an inspection mirror and a flash light. If everything looks good I fill 1/4 full with water and heat to boiling again and cool it and then rinse again with water and then pour in a quart of starsan and cover with 2 layers of Aluminum foil secure with a rubber band around the spear housing and pick up the keg and try to get it all over the insides. leave covered with foil until use. Once the keg has been cleaned this way you can just soak after fermentation and do a good rinse and it is ready for Starsan. Always look inside for signs of unclean areas with a strong light and inspection mirror. I want to rig a hot water heater just for cleaning kegs so I can rinse with hot water on a cleaning stand using a sprayball.