Ask The Brewmasters

What does your CIP consist of (process, chemicals)? I’ve seen this occur with the use of an oxidizer which wasn’t thoroughly mixed and had enough contact time.

Sent from my iPhone


Original Message:
Sent: 6/2/2022 3:24:00 PM
From: Derek Allmendinger
Subject: Black Patina/Staining of Stainless



Hey folks, I need your help. We've got a five year old brewhouse and recently I noticed a tri-clamp from our combo mash/lauter that had changed colors from the usual stainless to a black color. I later noticed that the manway door and half of the jacketed portion of the interior had also turned colors. I don't believe this was a gradual change, but rather a quick one. Any ideas what caused this and/or if it can be reversed? Could it potentially be causing flavor issues downstream? Thanks!

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Derek Allmendinger | Head Brewer

Hi Derek

I would first ask who manufactured the equipment and where the steel came from? Did the steel meet minimum requirements of Chromium?  Was it passivated?

Lastly.  Are you using any unusual cleaning chemicals?

Jim

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James Holden
Brewing Consultant
Retired but busy
jholden007@hotmail.com
Canada/US/Mexico
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Original Message:
Sent: 06-02-2022 15:24
From: Derek Allmendinger
Subject: Black Patina/Staining of Stainless



Hey folks, I need your help. We've got a five year old brewhouse and recently I noticed a tri-clamp from our combo mash/lauter that had changed colors from the usual stainless to a black color. I later noticed that the manway door and half of the jacketed portion of the interior had also turned colors. I don't believe this was a gradual change, but rather a quick one. Any ideas what caused this and/or if it can be reversed? Could it potentially be causing flavor issues downstream? Thanks!

--

Derek Allmendinger | Head Brewer

Hello Derek,  
This visual is reminiscent of steam induce corrosion, magnetite vs. hematite, where the hematite is iron oxide corrosion in a high temperature/chloride water environment and magnetite in a steam environment.  Can you speak to the possibility that this T/C and your vessel ID may have been over exposed to high temperature steam and aggressive frequency?
I am attaching before/after of very similar visual contaminant for a BioPharm Client.

To reiterate other comments, understanding whether any of the scope involved was chemically clean/passivated is good information to have as well as understanding your cleaning/sanitization SOP.

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Robert Schuck
Sr. Technical Sales Manager
Astro Pak
Costa Mesa CA
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Original Message:
Sent: 06-02-2022 15:24
From: Derek Allmendinger
Subject: Black Patina/Staining of Stainless



Hey folks, I need your help. We've got a five year old brewhouse and recently I noticed a tri-clamp from our combo mash/lauter that had changed colors from the usual stainless to a black color. I later noticed that the manway door and half of the jacketed portion of the interior had also turned colors. I don't believe this was a gradual change, but rather a quick one. Any ideas what caused this and/or if it can be reversed? Could it potentially be causing flavor issues downstream? Thanks!

--

Derek Allmendinger | Head Brewer

Original Message:
Sent: 6/2/2022 3:24:00 PM
From: Derek Allmendinger
Subject: Black Patina/Staining of Stainless



Hey folks, I need your help. We've got a five year old brewhouse and recently I noticed a tri-clamp from our combo mash/lauter that had changed colors from the usual stainless to a black color. I later noticed that the manway door and half of the jacketed portion of the interior had also turned colors. I don't believe this was a gradual change, but rather a quick one. Any ideas what caused this and/or if it can be reversed? Could it potentially be causing flavor issues downstream? Thanks!

--

Derek Allmendinger | Head Brewer

We saw some black/gray discoloration of our heat exchanger plates and around the edges of our brewhouse vessel lids one year that suddenly showed up.   We narrowed it down to our caustic cycles and possible overheating of the caustic during cleaning, but our chemical vendor never was able to specifically find out what had changed in their caustic that might have caused the discoloration.     They assumed that there may have been some upstream changes to chelating agents in the caustic that they were buying from their suppliers or something in the chemical makeup was interacting with something in our city water.   We sent samples off to a metallurgist and never found any corrosion or damage, just the staining.    It would come off by using a buffing wheel or polishing wheel but nothing else removes it.      It kept happening for over a year and then suddenly stopped.     Good luck in trying to narrow it down.

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Curtis Holmes
Alaskan Brewing Co
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Original Message:
Sent: 06-02-2022 15:24
From: Derek Allmendinger
Subject: Black Patina/Staining of Stainless



Hey folks, I need your help. We've got a five year old brewhouse and recently I noticed a tri-clamp from our combo mash/lauter that had changed colors from the usual stainless to a black color. I later noticed that the manway door and half of the jacketed portion of the interior had also turned colors. I don't believe this was a gradual change, but rather a quick one. Any ideas what caused this and/or if it can be reversed? Could it potentially be causing flavor issues downstream? Thanks!

--

Derek Allmendinger | Head Brewer

Weird question: does it have a smell to it? I think I saw that happen with a plated part (I don't know the metallurgy) that reacted with high concentration phosphoric/iodophor solution. It had a distinctly unpleasant odor.

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Chris Bogdanoff
Head Brewer
Heroes Restaurant and Brewery
Rancho Cucamonga CA
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Original Message:
Sent: 06-02-2022 15:24
From: Derek Allmendinger
Subject: Black Patina/Staining of Stainless



Hey folks, I need your help. We've got a five year old brewhouse and recently I noticed a tri-clamp from our combo mash/lauter that had changed colors from the usual stainless to a black color. I later noticed that the manway door and half of the jacketed portion of the interior had also turned colors. I don't believe this was a gradual change, but rather a quick one. Any ideas what caused this and/or if it can be reversed? Could it potentially be causing flavor issues downstream? Thanks!

--

Derek Allmendinger | Head Brewer