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"Passivation Tank Liner?"

January 15, 2010

Is there some sort of spray on liner that can be used for passivation tanks? Any idea what they use on the inside of 18 wheeler loads that haul it?

Any help would be greatly appreciated!

Wes Oettinger
Manufacturing - Chattanooga, Tennessee

January 18, 2010

Hi, Wes. Yes, vinyl plastisol can be sprayed onto a tank to resist passivation solutions. Remember, however, that processing tanks, unlike 18-wheeler loads, tend to involve some messy splashing of the passivating solution on the outside of the tank with no regular maintenance. To quickly appreciate this difference, recognize that when processed work is removed from the tank to carry it to the subsequent process step, it will be dripping.

For this reason, plastic tanks may be appropriate for a processing shop even when lined metal tanks are more appropriate for an 18-wheeler.


Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

January 22, 2010

In addition to Ted's comment, plastisol coatings won't cure properly at room temperatures. It should be cured at around 160 C. So, unless you can remove the tank from the process line, spray it, and then put it into a curing oven, you probably shouldn't consider plastisol as an option. Polypropylene tanks are well suited for passivation solutions with the exception of Type II (nitric+sodium dichromate). If you can't replace the tank, then you could purchase a flexible PVC liner that is premade to your tank dimension. There are various material grades and thicknesses available depending on your budget. Flexible liners typically need to be replaced every few years, but they sometimes last much longer.

Jon Barrows
Jon Barrows, MSF, EHSSC
Independence, Missouri

February 6, 2010


Is this nitric acid passivation or citric acid? Citric acid is an iron scavenger and is not nearly as aggressive as nitric acid so you should consider using stainless steel tanks unless there is nitric acid,chrome or HF in the chemistry. If a liner is necessary, I agree with the previous post regarding polypropylene as a rigid tank liner or a polypro tank.

Doug Trageser
- Chattanooga, Tennessee, USA

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