Kegs that are typically used for homebrewing are called a lot of things, including corny kegs, homebrew kegs, soda syrup kegs and others. So what are these kegs exactly? These kegs were originally used to dispense soda, but most of this usage was replaced by bag in box.

As these kegs were released from soda companies they were quickly adopted by homebrewers because they are the perfect keg for homebrewers, home soda makers, Kombucha, coffee and carbonated water. These kegs will basically last indefinitely if properly maintained and protected. The Cornelius company first released these tanks in 1957, so some of them are almost 70 years old now.

What maintenance needs to be done on these tanks? Well the good news is that not really all that much. The main areas for maintenance are the keg lids, the posts, poppets and the o’rings. Another area that can occasionally have an issue is the rubber bottoms or tops separating or the kegs splitting because liquid was left in them under pressure and the keg basically fails from the expansion of the ice under pressure. We will cover each of the scenarios.

Cleaning the Kegs - I am not going to go into great detail on cleaning the kegs because I have already written a separate article I will link to called “How to Disassemble and Clean a Corny Keg” This article and accompanying video. I recommend you watch this video for maintenance as well as it will show you how to take off the posts and replace the poppets.

Replacing Poppets and/or Posts -

• Poppets - If you are having issues with leaking from your poppets you can replace the poppets with the original style or with universal poppets. I like using the universal poppets because they will fit any keg and the legs don’t bend like on a normal poppet because they use a spring. I have literally used these in thousands of kegs and they are fantastic.
• Posts - Posts sizes are a little more complicated, but once you know what thread your keg has it is easy to find a replacement, if one is available.
  • Cornelius and AEB ball lock posts and pin lock posts all use the same size thread post, it is 19/32”-18.
  • The vast majority of Firestone, John Wood RA, RC, Hoover and other pin lock use posts that are 9/16”-18. For these posts click here.
  • The vast majority of Firestone (and other brands besides Cornelious) ball lock kegs use 9/16-18 on gas post and ⅝”-18 on liquid post.
  • The exceptions on post sizes are the racetrack style kegs. These are recognizable by the lid shape. Normal kegs (both pin and ball lock) have an oval or egg shaped lid, while “racetrack” lids literally look like a racetrack with round ends and very straight sides. These kegs use posts that are no longer available, but we can sometimes acquire used ones if you want to call us. These kegs were made by Firestone (Challenger), John Wood (85) and possibly others. The posts they use are 11/16” -18 on gas, but ¾”-18 on the liquid side. They also use a plastic post insert.

We also have a chart showing this information, click here to see chart.

Lids - These are fairly straight forward and easy to maintain. There are basically two types of lids in normal use today. These include a ball lock lid with a manual (and auto) pressure relief valve and a pin lock style lid that only has an auto relief valve. There are lots of other lids on the market, but most people have replaced these with one of these two types. Lets go over these.

• Ball lock style lid with Auto and manual relief - As you can see in the link, we sell these lids new. This was the preferred lid by most people because you can relieve pressure manually and the pressure relief valve is easily replaceable. You can use these on pin lock kegs in addition to ball lock.
• Pin Lock Style lid with auto pressure relief valve - These lids work well, but are not quite as popular as the manual style discussed above. As far as functionality they are absolutely fine to use on either a pin lock or ball lock lid. Even without the pressure relief valve you can easily relieve the pressure by pushing on gas post with a pointed object like a small screwdriver or you can use a Pin Lock Keg Poppet Valve Depressor to easily remove the pressure from a pin lock keg that uses this lid.
• Lid with no Pressure Relief Valve…well, sort of - There are a lot of lids out there that appear to have no pressure relief valve. At one time it was fairly common for soda companies to use these. If you look at the center of these you will see what looks like two Parentheses with a line in the middle (or similar). These are weak points that are designed to blow out before the keg ruptures. The lid is destroyed in this process.
• Plastic Lid - Yep, you read that correctly. At one time plastic lids were made to save money because of the cost of stainless steel. This probably seemed like a good idea at the time, but these are very old now and I absolutely would not trust them. If you have one you should replace it with a stainless steel lid!
• Flat Seal Lid with Pressure relief Valve - Unlike the first listing on these bullet points, these sealed flat on the inside of the lid and no one makes replacement valves anymore. If they work, they work, but if they are leaking they cannot be replaced. Sometimes cleaning and lubing the o’ring or rubber seal that connects to the lid body will get them working again for a while.

Repairing and maintaining Lids -

• An important thing to do on lids is keep a good keg lid o’ring on them and keep it lubed. Discard at first signs of cracking or drying up. They can also become too flattened out and need to be replaced for a better seal.
• Lubing or replacing pressure relief valve - When you remove a manual pressure relief valve from a keg you will see either an o’ring or rubber seal on the bottom. You should lube this with o’ring lube on a regular basis.

Other issues with Kegs - Here is a list of some other common issues with corny kegs and how to address them:

• Loose rubber tops and bottoms - This is a very common issue with used kegs. Over the years the rubber top or bottom has come off completely or is coming off in one area. We have found that a product called MasterSeal NP1 is excellent for re-securing the tops and bottoms. I have never had a top or bottom come off again after using this, assuming you are using it in a home environment. If the top or bottom is just partially coming off just clean it out, let it dry and push some of this inside with your caulk gun where it is coming off and put something heavy on the top of the keg while it cures.
• Split or cracked keg - This typically occurs because liquid was left in the keg while under pressure and it was allowed to freeze. We have never been successful in fixing these and doing so could be unsafe. Any keg with a split or crack in the stainless steel should be discarded.
• Mouth will not seal with lid - This is likely caused by an uneven place in the mouth of the keg. You can generally feel the defect if you run a finger along the inside edge of the mouth. We used to automatically scrap these kegs, but we have had a lot of success fixing these using a vice grip or locking pliers to straighten out the part of the mouth that connects to the o’ring on the lid.
• Keg Badly stained inside - You can usually get these clean using a strong solution of Brew Clean, soaking and brushing or you can try Bar Keepers Friend as well.

Well, that about sums up what you need to know to maintain and repair ball lock and pin lock kegs. I have been using and working with these kegs now for over 20 years. There have been so many made in so many configurations that I still learn new things about them. If you have any questions, comments or additional knowledge on the subject I encourage you to email me at tburns@kegconnection.com or call us at 325-356-5204. Happy Kegging!