Passivation in a brewery

By June 2, 2016Chemicals, Piping, Tanks

Passivation is an important part of CIP, sanitation, and efficiency in your brewery.  At the end of the day, you wind up with a thin layer of chromium oxide on the surface of your vessels, which strengthens the steel, makes for quicker and more effective CIP, and saves you money.

Click here for a detailed set of instructions for passivation.  Thank you to Ecolab for providing this sheet.

What does this have to do with brewery wastewater?  It’s actually very relevant, and there are several issues mostly revolving around what to do with the passivation solution when you’re done with it.  But I’m also here to help you out, so here goes:

  • If you dump a large volume of spent passivation acid down the drain, you will create a significant low pH spike.  This can negatively affect everything between your point of discharge and the outlet of your local wastewater plant.
  • If your drains or drain piping are made of cast or ductile iron, you can dissolve away your drains and pipes!
  • Same goes with any cast iron wastewater pumps you might have.
  • If you have a nice tile floor, it can also dissolve the cement in your grout!
  • By it’s nature, passivation happens at slow times of the year, maybe around the winter holidays.
    • This means there is not a lot going on in your brewery and not much dilution happening with your wastewater.
  • Passivation acid can be stored and reused, but it tends to be a large volume and space can be an issue.  Also reheating it can be tricky depending on your CIP system.

Don’t want to deal with all of this?  You can specify passivation of your brewing and fermentation equipment (and kegs!) at the factory prior to shipping.  Like anything, it’s all in the contract details.  Most reputable suppliers offer this already, but it is very important to be clear about this.

When to passivate?  If your equipment is already passivated, you’re in good shape for many years.  However, if you modify the vessel or damage the surface somehow, you should re-passivate.  Drop something heavy inside your brew kettle and scratch it?  Weld a port in to a pipe?  Create a new stretch of hard pipe?  Then passivate.

Is it passivated or not?  There are test kits available to check this.  Some are expensive and others are inexpensive.

Hope this was helpful for you all.  Thanks for reading, John

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