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magnemelhus
03-07-2016, 06:55 AM
Hi all,

I am firing up our used 7 bbl Portland Kettleworks system for the first time, and need to run an acid CIP to remove the scale and mineral buildup from the previous owners. There are a couple major problems though: for one, the outlet at the bottom of the tank is on the side, and there is a lot of water on the bottom after it is done draining, making it potentially very hard to rinse out any residual chemicals. The other, and more trouble problem, is that the outlet pipe is 1" copper, and will not tolerate the acid... Caustic/PBW is not going to cut it in this case, is there anyone who knows about a product that will take off minerals and scale but won't corrode the copper pipes?

Brian@Loeffler
03-07-2016, 10:30 AM
My recommendation is to try and replace the copper with stainless steel. This will be necessary during passivation of the tank and other stainless steel in the loop, even if it requires soft piping the CIP loop during this passivation. Nitric Acid is typically used for passivation of stainless steel, but will be too aggressive for the copper. At passivation concentrations, it will be too aggressive for even one cycle. I also recommend you implement a lower outlet that will allow complete draining of the vessel. Not allowing vessels or process piping to completely drain will drastically increase water use during rinsing. When the tank is unused, it will allow water to stagnate.

If you cannot replace the copper, you must modify the chemical regimen. The cheapest solution (aside from replacing the copper) would be to use a copper-inhibited caustic. When used on copper, caustic products must use a copper inhibitor to prevent corrosion. This can be a pre-inhibited caustic or an actual inhibitor added to the current caustic you use elsewhere in the brewery. Alternatively, you could use a non-caustic cleaner, albeit this is a more costly route long-term. For acid cleaning, I recommend a mild citric or Phosphoric Acid at 1% v/v at ambient temperature. This will have a mild attack on the copper, so it should be performed only when scale removal is needed.

I recommend contacting the previous owners of the equipment to determine their CIP regimen. If acids do not remove the scale build-up, it is also possible the scale is not calcium oxalate (beerstone) or calcium and magnesium (hard water) scale. It is very, very common for non-caustic products containing Sodium Metasilicate to leave a white scale that is very difficult to remove with an acid cleaner. These scales can be removed, but with products incompatible with the copper.

jebzter
03-07-2016, 10:38 AM
Is the kettle stainless? It is not a good idea to have a copper pipe brazed or otherwise attached to any kind of steel in any water environment, the galvanic reaction alone will eat the copper. Is it copper clad stainless? You are good to go if it is just copper clad.

dick murton
03-07-2016, 11:19 AM
If it is a hot liquor tank, then as Brian says, you need to make those two important changes first, with a drain to sewer drain point on the new low point outlet to allow you to drain easily and fully. And then wash with nitric. My experience is that caustic is a waste of time for hard water scale (predominantly carbonates, but possibly a small amount of sulphate, which is loosened/washed off as the carbonates are dissolved), but if they have "cleaned" with other materials and left a non carbonate scale, it will be time to talk to a reputable supplier to recommend the most appropriate detergent.

If you have electric heating elements, make sure these are all stainless steel as well, no brass, bronze etc, otherwise you won't have any heating elements left after descaling.

TGTimm
03-07-2016, 03:18 PM
All of what was said above re: get rid of copper, install new SS drain at low point. This doesn't need to be sanitary-grade, so a good place to practice your SS TIG welding!

We use sulfomic acid--Wesmar BSR--for de-scaling. If the tank shows no signs of rusting, passivation shouldn't be needed--except for around the new weld when you install the new drain.

Most electric elements are not SS, so if you go with a nitric wash, you'll have to pull the elements and block the holes off. I'd just go with a sulfomic acid wash.

Every few times we wash the HL tank, about quarterly, we do a caustic after the acid wash. It removes some interesting stuff, at least the water comes out very dirty.

Use the hottest water possible for the washes, but DO NOT turn on the elements while de-scaling!

forrestmz3005
03-08-2016, 03:43 AM
Rydlyme. Expensive stuff but does the job for copper tubing, should work for your setup.



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magnemelhus
03-11-2016, 08:47 PM
Thanks for the replies! It is a indeed a stainless tank with copper pipe threaded on a 1" stainless outlet, which is apparently raised about 1/8-1/4 inch from the bottom of the vessel, just a bead's width... I ended up climbing inside and scrubbing the worst of the scale off by hand with acid #5 and flushing well afterward. Point taken, though, in the future I will put a triclamp fitting on the outlet and have my welder fit up some 1" stainless to the hot liquor pump instead. Busy week, many tanks to wash and passivate, then I discovered that my heat exchanger was clogged... that was fun to pull apart, scrub by hand, and put back together! Successfully executed batch 1 today, so well worth the effort.