New Vessel Cleaning and Passivation

[dirtfish]

I am in the process of cleaning and passivating our tanks. I started with two 7 BBL conical fermenters and am not sure that I achieved acceptable cleaning or passivation. I followed the Five Star directions for initial cleaning with PBW, then passivation with Acid #5 (quantities are my own based on a minimal amount that still recirculates through the pump/hoses):

I made 4 gallons of PBW solution mixed at 2oz. per gallon at 160F and recirculated for 45 minutes @ ~2800 rpm.

Then rinsed well with the washdown hose at 160F.

Then rinsed with cool water and waited about a half hour for the tank to cool down.

Then made 4 gallons of Acid #5 solution mixed at 5 oz. per gallon at 120F and recirculated for 30 minutes @ ~2800 rpm.

No rinse, removed all fittings, opened door to air dry.

Here is what it looks like inside.

There is a dull residue at the top portion that does not seem right. The surface below this line seems ok.

Any suggestions?

[gitchegumee]

Rinse your tanks after acid!

Not sure where you obtained your passivation procedure, but look at other threads here to see the relevant standards and methods. Air drying is a myth. And one that has left many tanks discolored and stained when using nitric. Rinse your tanks after acid passivation unless directed by somebody who actually knows what they're talking about.

[Thirsty_Monk]

I would phased out PBW for other cleaner.

[dirtfish]

Phillip, I got the procedure directly from information that Five Star sent me. The only decision I made was how many gallons of solution to prepare for proper circulation. I had looked back at previous posts on this site and saw debate on both sides of the no-rinse position. I chose to follow manufacturer's recommended procedure for the product I was using instead of researching the ASTM standards. Many times I get stymied by too much information... I will be talking to Five Star to share my experience and get their input and also reach out to local breweries. Can you recommend what I need to look into to remove this haze? I'm guessing it is a mild pitting and needs to get gone in the interest of the longevity of the vessel.

Thirsty Monk- Anything more specific on another cleaner?... What? Why?

Thanks-

[gundersonchad]

five star super C.I.P.

If you are looking for a better cleaner within the Five Star product line-up, I would recommend Super C.I.P. Works very well in the brewhouse as well as FV's. When preparing a solution of Super CIP, make sure to whisk it like crazy into a 5 gallon bucket first, then add to tank.

[soia1138]

That residue is from not rinsing the acid. Philip is right, you always need to rinse cleaners. The basis of passivation is getting the surface clean, real clean, then rinsing and allowing to air dry. The air dry after rinse is the key to passivation, without it you passivate nothing. Oxygen needs to be able to react with the clean surface of the stainless. I know what the directions say on the five start bottle, I use it myself. They are wrong, as are many other directions on many things you will use. Passivation is passivation, there are no different ways to do it, only different chemicals to choose from for the cleaning portion.

[Thirsty_Monk]

Any chlorinated caustic works quite well. I like super CIP. It is powder and it needs to be well mixed otherwise it will leaves stains. In the area where it is hard to mix it, I use liquid cleaner. I prefer low temp cleaners.

After cleaner you rinse it well and follow with acid rinse for passivation.

[JustinDCrawford]

It's been a few years but if I recall this was how we pacified our tanks.

2 cups Glowsan 10 gallons of hot water. Let's say 160F. Cycle for a good 10 mins or so.
Hose it out.
2 cups De-greaser, just normal off the shelf. Purple Giant for example. 10 gallons water. 160F 10 mins.
Hose out.
1 cup BSR-10W, 10 gallons hot water. 160F 10 mins.
Hose out.
2 cups Caustic, 10 gallons hot water. 160F 10 mins.
Hose out.
1 cup Parasitic, 10 gallons COLD water. 5 - 10 mins.
Drain.
Ready for product.

[BnB Brew]

As far as I know, the only reason you need to let the surface air dry is to form the Chromium Oxide layer. Without the formation of this layer, you have no passivation. The thing is, Nitric Acid, the primary acid present (along with Phosphoric) in Acid#5 is an oxidizer. It prepares the surface and oxidizes it at the same time. So, I don't see the point of leaving the surface to air-dry after this step... Unless I am missing something.