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How to Passivate Stainless Steel Brewing Equipment

Oct 20, 2023
yanan

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Stainless Steel Brewery Equipment，Brewing Equipment

How to Passivate Stainless Steel Brewing Equipment

It is common for brewing equipment to use high-grade stainless steel. Although stainless steel is hailed as the perfect metal for beer brewing, it can corrode or rust. Craft breweries, home breweries, wineries, how to "passivate" your tanks and equipment is very important. We'll learn how and why stainless steel corrodes, and how to passivate stainless steel beer brewing equipment to protect it.

Made of stainless steel, rust-proof

The chromium in stainless steel reacts strongly with oxygen and actually forms a protective layer of chromium oxide on the surface of the steel. This chromium oxide prevents rust and corrosion. However, if the chromium layer is damaged for any reason, the iron in the steel may actually begin to corrode and rust.

Stainless steel brewing equipment is generally very corrosion-resistant. However, the protective layer may wear away if exposed to bleach or other bleach-based cleaners, scratching, scrubbing, exposure to non-stainless steel scouring pads (such as steel wool), or contact with regular steel.

Stainless Steel Brewery Equipment，Brewing Equipment

What is tank passivation?

The brewing process chemically treats stainless steel. Today, most brewing tanks are made of stainless steel. The purpose is to form an invisible layer or coating on the inner tank wall, thereby protecting the metal from corrosion and pitting caused by:

Cleaning chemicals (acids, corrosives and disinfectants)

CO2 and beer

Chlorides (such as salt) are very hard on stainless steel

Beer with low pH

There are other causes of corrosion, but these are the main ones. Before we delve into passivation, we need to understand descaling/pickling.
Stainless Steel Brewery Equipment，Brewing Equipment

What is descaling and pickling?

Rust removal and pickling should not be confused with passivation. With older tanks, you will have sediment buildup that will need to be cleaned out (oxides removed). Before we discuss how to passivate your brewing vessel, you must first clean the exposed metal to ensure successful passivation.

Traditional passivation

Both chemicals were often used in this old method. They are citric acid and nitric acid. Citric acid is a mild organic acid that chelates iron well but leaves no protective layer behind to protect your tank. Using citric acid can leave your tank vulnerable to chemical attack when you further clean it after use. Nitric acid is most commonly used by breweries when passivating tanks.

The main problem with this method is that the layer is not permanent and is not usually repeated in the brewery. Due to the dangers involved in using nitric acid at such dangerous concentrations. You will need to passivate your tank using the above method at least twice a year. The new method we describe below will help keep your tank clean and in top condition.

Conversion coating passivation

To most brewers, the idea of cleaning first with an acid cleaner and then with an alkaline cleaner may seem counterintuitive. The methods used include alkali cleaning, rinsing, pickling and final rinsing of the tank. This method is very effective at removing proteinaceous dirt, but is less effective at beer stone and will not dull the metal over time. Over time, the result is soil buildup and microbial corrosion (MIC) of metals. If this continues, it can cause pitting of the metal and put you at a higher risk of infection. Because it is difficult to clean and disinfect water tanks.

When should it be passivated?

With new equipment, a lot depends on where the equipment comes from. High-end equipment is often soaked in nitric acid during one of the last steps in production and may only require a good cleaning to remove oil residue before first use. For cheaper, often foreign-made equipment, many manufacturers machine, weld, polish and machine the steel which may be protected at some point, but they may skip the final dip coating after fabrication to save funds.

We prefer to use new stainless steel equipment for a thorough cleaning and passivation step. Either way, a thorough cleaning is required to remove oil, polish, and other contaminants that could ruin your beer. The extra step of passivating it after cleaning is not expensive since stainless steel equipment is relatively expensive and lasts a lifetime.

in conclusion

Keeping your tanks passivated will help your beer perform at its best. If you are not sure which chemicals are used in this process, your chemical supplier should be able to help.

Doing an acid clean, draining but not rinsing, and then immediately doing an alkaline clean is what metallurgists call a phosphate/silicate coating. This passivation technique differs from the high-concentration nitric acid method, which leaves a chromium oxide layer on the metal. The phosphate/silicate coating method provides some passivating properties without the use of dangerously high concentrations of chemicals and saves time by eliminating the need for 24 hours of air drying. It's safer, simpler, and will continually keep your tanks clean and passivated.

If you are planning to open a brewery. TIANTAI BrewTech could help you answer your questions and supply the brewery equipment system. We supply 2-150bbl complete beer brewing brewery equipment system including malt milling equipment, brewhouse equipment, fermenters, brite beer tanks, beer bottling machine,beer canning machine, beer kegging machine, hopping machine, yeast propagation equipment. We also supply all auxiliary brewery systems like steam heating pipe and valves, water treatment, filter, air compressor etc. Everything in brewery are all in our list.

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