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  • 1.  Heavy scale on HLT tank internals - difficult access

    Posted 08-11-2025 09:41

    Gday Brewmasters,

    A client of mine has heavy scale in their steam-jacketed Hot Liquor Tank, they haven't cleaned/acid washed for over 6 years. See pic attached of heavy brown scale on the internals of the tank.

    Unfortunately it has really bad access which makes it unsafe to enter or scrub by hand. We've tried 10% hot citric solution sprayball cycle, and the same with 4% caustic cycle and a phosphoric/nitric cycle, but this won't budge!

    What else should we try to get rid of this?

    Heavy scale formed on heating jackets



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    Sam Williamson
    Williamson
    Auckland
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  • 2.  RE: Heavy scale on HLT tank internals - difficult access

    Posted 08-11-2025 17:28

    Hi Sam,

    My experience with heavy calcium scale in HLT is at least 2 mm thick, nicely coated in them due to the use of spring water. My team ran with the suggested acid ( I think it was nitric acid) at the % by the chemical supplier, and the scale came off just fine without scrubbing. I do not think you need a caustic run. A couple of tips for you:

    1. check the spray ball/device to ensure they are free of any clogs
    2. let the surface sprayed on with acid then rest for a few minutes, repeat the process for a short run, drain it and restart with a fresh cycle
    3. make sure running at the right temperature by the supplier, I think generally it is around 50 degree Celsius and not exceeding 60 degree
    4. be careful any falling scale can clog the pump, pipe, and even lauter tun spray ball! so make sure rinsing everything thoroughly

    Cheers,



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    James Yii-Jen Tien
    Whitby, ON
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    Original Message


  • 3.  RE: Heavy scale on HLT tank internals - difficult access

    Posted 08-11-2025 22:09
    A sulfamic acid based cleaner could work. An example is Durgol Universal(TM). Anther possibility is methanesulfonic acid: Durgol Bio (TM). Check SDS for safety info.

    Roger Barth, PhD
    Professor Emeritus of Chemistry
    West Chester University
    rbarth@wcupa.edu

    Author of
    The Chemistry of Beer, The Science in the Suds, Second Edition. ISBN 978-1-119-78333-0
    Mastering Brewing Science: Quality and Production, Second Edition ISBN 978-1-394-20699-5

    ________________________________

    This e-mail message was sent from a retired or emeritus status employee of West Chester University.


    Original Message


  • 4.  RE: Heavy scale on HLT tank internals - difficult access

    Posted 08-12-2025 12:43

    A long time ago I took over a brewery that had some neglected equipment and I used a nitric acid  solution that I used at %15 and soaked it for a full work day in the brewery with alkaline cycle to follow to neutralize any leftover acid and it seemed to work.  I would avoid trying to hand scrub the inside of a tank because you can cause unforeseen damage to the metal and of course safety is a major factor in this as well.  



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    Landon Swanson
    Head Brewer
    Pueblo Vida Brewing
    Tucson AZ
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    Original Message


  • 5.  RE: Heavy scale on HLT tank internals - difficult access
    Best Answer

    Posted 08-12-2025 16:02

    Hi Sam:

    It looks like your tank has lost its passive layer and started rusting as a consequence.  The Citric Acid has probably removed some or most of the hard water scale in the tank, but it will not remove the rust.  While Citric Acid is a great sequestering agent and can be used successfully against iron oxide deposits, this is an application for a strong Nitric Acid solution, ideally mixed with some Phosphoric Acid.  I would recommend using a 20 - 40% Nitric Acid solution and circulate the solution at ambient temperature through your sprayball for several hours.  It may take as much as 12 - 24 hours of contact time to convert the rust on the surface and turn your vessel back into stainless steel shine.  It may take more or less time and you may have to add additional Nitric Acid to the solution since the rust and any potentially leftover scale deposits can break down the Nitric Acid over time. 

    Once all the rust has been removed, run a separate passivation cycle with a fresh Nitric Acid solution at about 10% for another 60 - 120 minutes ambient.  Then rinse and you are good to go. 

    I generally recommend to frequently descale the hot water tank with an acid and passivate the hot liquor tank about every three to six months.  The frequency depends on your water (pH, water hardness, chlorides, etc.) and the composition of your water.  The more chlorides, the more frequently the tank should be passivated.

    I hope this helps and we had tanks that took up to several days to turn back around. So don't give up if it appears to take a while.  You should see improvement over time though.

    Cheers,

     



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    Dirk Loeffler
    Executive Vice President
    SEKA Chemicals
    (404) 600-1910
    loeffler.dirk@sekachemicals.com
    ------------------------------

    Original Message


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