All Corny kegs are assembled from many stainless steel parts and a number of rubber O rings. Most of these parts come into contact with the beer and therefore must be cleaned and sanitized before use. With careful disassembly and assembly, none of the stainless parts should ever need replacement. O rings can eventually dry out, crack, get cut, or simply get lost. One of the real advantages of Corny kegs is the wide availability of standard replacement parts. Most larger homebrew supply shops and mail-order suppliers will have all the parts you need, and several national distributors of restaurant and beverage supplies also carry all replacement parts.

The view from above a typical Corny keg with lid removed. Lids can come in different styles, with or without a pressure relief valve (top). The O rings from reconditioned kegs (shown around the lids) should be thoroughly cleaned or replaced.

Because many home brewers acquire used, reconditioned kegs, and because there's no way of knowing where that used keg came from, it's always a good idea to disassemble used www.kegs.completely and inspect them for damage (such as pitting or rust spots inside), residue, and general cleanliness. The kegs may well need a good scrubbing with B-Brite.

Disassembly and Cleaning
The lid: It should be easy enough to remove the lid and the large O ring used to seal it when the keg is depressurized by lifting the retaining bail (the lid won't budge if the keg's under pressure). Often the O ring will smell strongly of soda syrup. The smell can be removed by washing in warm soapy water. Many brewers prefer to buy an O ring kit to replace all the rubber parts to eliminate the syrup odor. I've never found the original O rings to have any effect on beer aroma or flavor, but the choice is yours. These large rings cost about $4 (about $7 for a kit). In any case, the O ring should be removed from the lid, and both parts thoroughly washed and reassembled, along with the retaining bail.

The inside: A newly purchased keg should be very clean inside and not require any special treatment. An effective way to wash the interior, if it's needed, is to add about 1-2 tsp of nonperfumed dishwasher detergent or TSP to about 2-4 qt of the hottest tap water available. With the lid in place and locked, shake the keg repeatedly, then drain and rinse. Usually, the kegs you buy will have only been used as soda canisters, and any residue they contain is easily water soluble.

Kegs can be harder to clean after you've used them for beer making because of beer stone, protein deposits, trub, and so forth. A standard carboy brush will come in handy for loosening gummy material. The dishwasher detergent will then leave the keg bright. It's sometimes difficult to tell whether the keg is completely rinsed, so after draining all detergent water I rinse three times -- twice with very hot water, and a final time with cold water.

The connector valves: Two valve assemblies, also at the top of the keg, allow the rapid connection and disconnection of the gas pressure line and the beverage dispensing line. These poppet valves are designed so that gas pressure inside the keg seals the valves shut when the keg is not connected during storage and transport. The gas and beverage hoses connect to these valves using "quick-disconnect" fittings. The valves and matching fittings come in either a ball-lock or a pin-lock style, which are just two different ways to couple the fitting to the valve.

Examples of a pin-lock (left) and a ball-lock keg.

Remove. The two valve assemblies thread onto the keg like any nut to a bolt. For ball-lock kegs, use any wrench or socket that matches the fittings (one is usually a standard hex shape, and the other usually a 12-point style), turn them counterclockwise, and remove them from the keg. On pin-lock kegs, the gas-side connector uses two pins 180 degrees apart, and the beer side uses three pins 60 degrees apart. The pins make it difficult to get a wrench on the beer side. Many brewers modify a spark-plug socket wrench by cutting slots in the corners for the pins to fit into, which prevents accidental snapping of the pins off the connector.

A ball-lock keg with disconnect fittings, gas hose, and beer hose with picnic tap. The IN and OUT fittings on a ball-lock keg have very slightly different diameters. The mnemonic for connections is Gray = Gas, Black = Beer.

Clean. Each of these valve assemblies consists of two main parts: the threaded connector that you just removed, and a poppet with a spring pressed into the housing. These valves can usually be cleaned with no further disassembly by simply hand-agitating them in hot soapy water (soak if needed). If you feel it is necessary to clean the poppet or replace one that no longer seals, simply depress the poppet into the housing with a nail or dowel and it will pop out the bottom. Reassembly is simply a matter of pressing it back in.

Inspect the O rings. Inspect the exterior O rings for damage, and replace them if they've been cut. They can be removed from the valve housing using a small screwdriver -- be careful not to use too sharp a tool.

Sanitize. Soak the valve assemblies in iodophor before reassembly.

The gas (IN) fitting of a pin-lock-style keg has two pins; the beer fitting has three. The poppets in these valves allow the keg's gas pressure to seal shut when the keg is not connected.

The beer and gas tubes: Remove. After you've removed the valves from each side of the keg, you'll see the two threaded connections integral to the keg. In the hole of each connection you should find a stainless steel tube. The tube on the gas side of the keg, the side marked IN, is only about 3 in. long; the other tube, on the beer side marked OUT, is much longer and reaches to the bottom of the keg. Remove both tubes by simply reaching into the keg and pushing the tubes up and out.

Clean. The top of each tube is flared outward to retain the O ring and to prevent the tube from dropping through the hole into the keg. Carefully remove the O rings (original equipment on many kegs is often a rubber washer), and clean them and the tubes with warm water and detergent. A long tubing brush is handy for thoroughly cleaning the interior.

The pin-lock-style fittings on this keg are not interchangeable with ball-lock connectors. Thus, it's usually best to stick with one style of keg.

Reassembly
Reassemble the keg by inserting the long dip tube into the OUT side of the keg and the short tube into the IN side. Thread the valves back on, remembering to put the gas and beverage valves on the correct sides of the keg.

Sanitizing
When you're ready to rack from your fermentor to the keg, add about 2 qt of iodophor solution to the keg, seal it with the lid, and agitate. Rock the keg enough to get sanitizer inside both dip tubes, and occasionally invert the keg and depress the pin in the center of the valve housings using a large nail or other tool to allow any sanitizer in the tubes to drain out the valve assembly and sanitize difficult-to-reach parts. After a few minutes of agitation, I drain the sanitizer into an open pan and use it to sanitize the racking tube and cane. (Be sure that all the solution is drained from the long tube by standing the keg upright and depressing the OUT connector.) Leave the keg inverted in a clean container while you prepare for racking.