Stainless steel is one of the unsung heroes of the brewing world. So much of what brewers do would be more difficult, if not impossible, without the benefits stainless steel provides. However, without proper care, you can lose those benefits.
What sets stainless steel apart? A Chromium oxide layer. This layer acts as a protective “shell” on the surface of your stainless steel. However, this layer isn’t impervious. Dissolved metals, such as iron, will build up over time inside your tanks. While your stainless steel doesn’t readily oxidize (rust), these free metals can… and do. As the microscopic bits of metal rust, they can create “pits” in your stainless steel. Pits are exactly what they sound like; tiny nooks and crannies. This pitting can have 3 extremely adverse effects on your metal:
- Pits are a great place for microbial growth to grow and fester
- Oxidation can eventually move into the stainless steel itself
- Eventually your equipment will be damaged and likely result in wasted batches
So how can you prevent this from happening? Passivation! And when it comes to stainless steel tanks and lines, passivation isn’t an option… it’s a requirement.
What is passivation? While the chemical process is complicated, it’s conceptually simple. Applying a solution of strong acid to the surface of stainless steel and then allowing it to dry will produce a chemical process that results in the regeneration of your protective chromium oxide “shell”. A good way to think about passivation is that it’s like seasoning cast iron periodically. This process is also great since it helps to remove a large amount of the “free metals”, like iron and zinc, that can cause pitting.
Another important question to answer is the frequency at which passivation should be done. Although this can be hotly debated amongst brewers, there’s no standard answer across the board the answer depends on the volume you’re pushing through your tanks, how often you’re doing an acid CIP cycle, and the mineral content in your water. At a minimum, passivation should be done every 6 months. In the most extreme situations, every 2 months might be needed. More than that, and you’ll run into diminishing returns on your invested time.
Passivation can have added benefits beyond the obvious. Your equipment will last longer, you’ll leave microbial growth with a less inviting environment, and you’ll improve your overall CIP program, as soils will release from the surface of your stainless far easier.
So, what should you use to passivate? A-CIP Acid CIP cleaner is perfect to get the job done. A-CIPC can also be used as an acid rinse in your CIP process by dialing back the concentration used, making it a 2-in-1 product!
A-CIP is available in 5-gallon, 15-gallon, 55-gallon and 275-gallon quantities.
Contact SISbrew for more info.
Cheers!