Feasibility of internally coating an air compressor tank with a fluoropolymer

I’m wondering if I bought a 120 gallon vertical compressor tank would it be cost effective to have a 6" ferrule welded on the top and have the internal carbon steel surface coated with some kind of chemically resistant fluoropolymer like PTFE vs buying a stainless steel reactor vessel?

It seems like a no-brainer, you get a MAWP of 200 PSI out of most compressor tanks and they’re available second hand for next to nothing. @Soxhlet I assume you’d be the right man to ask but anyone’s input is welcome…

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Idk if tanks are made of cast iron or not, in which case I could see the weld being a point of failure but I don’t know much about this kind of thing, so someone correct me please.

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The welded seams I see on my tank are making me think that the tanks are not cast.

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sounds like a more expensive and less durable solution than a proper solvent tank.

Well nobody’s going to be hitting the tank with a hammer so durability aside. Chemical resistance, pressure rating, and cost are my 3 main concerns.

The only thing I see wrong with using a carbon steel tank is I’m worried about corrosion when an extract laden solvent is in contact with the carbon steel for extended periods of time. It’s already rated for higher pressure than it would be exposed to in its new service life and it’s MAWP definitely isn’t the burst pressure so there’s still a decent margin of safety factor.

Really the question should have been, cost of welding ferrule + cost of internal coating of fluoropolymer + price of compressor tank vs having a stainless steel tank of the same capacity made in China and shipped to me.

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I dont see any reason this couldnt be done. its most likely going to have visible welded seams on the inside that could catch impurities or bacteria but it should be fine for most.

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I have been using ss ship fire extinguishers
For a while now rated to 300 psi
316 ss 150 L volume and cheap
Mine are 4 mm thick and build on wheels

My next favorite are solar powered heating boilers Some good brands use ss 316 but most use 304 rated till 180 psi some and most to 150 psi biggest advantage
Coils or jacket inside
Factory made insulation mantel

and last the scrapp yards give a business card and tell them any stainless tanks to call you and pay double the price of scrap

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Spray a ceramic coating and bake it at like 1000°F

Came here to mention this.

FYI, it’s a much smaller problem when an air compressor tank leaks so beware the really bottom-of-the-barrel ones. I’d suggest, following the requirements of B31, that you look for something rated for 350psi if it’s going to have hydrocarbons but you should be good as long as you take reasonable precautions.

Also, obviously make sure the coating use doesn’t let a bunch of phthalates dissolve into it; rust is safer than plasticizers. Seems like @Roguelab’s system is a winner

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O by the way solvay the company
Now sells waterbound halar coatings a two step spraysystem for DIY

This post and idea is one of the most horrible ideas ever.

First of all you’ll encounter chemical leeching. The liner won’t stay put and you won’t be able to safely convert a air compressor tank since they aren’t made for cyclic pressure and temps. I mean at least to be certified for hydrocarbon gases.

There’s a reason why people don’t waste time with ideas like this.
The metal must be electropolished and prepared to accept a coating when brand new. The inside of that rusty tank won’t take any material to adhere to it.

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Don’t do it.

Delamination will come for you

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Everyone’s input but @spdking is welcome. Lol

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Why. Because I’m not encouraging someone to use a rusty non sterile and non corrosion free tank for having it lined? The liner won’t even stick if the inside isn’t like brand new with zero surface corrosion.

Have you ever seen the inside of a air tank.

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Post. A. Pic. Of. Your. Head. In . An. Air. Tank.

If ur gonna Talk the the talk- air tank

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“have a 6” ferrule welded on the top"

Once you weld on it it’s no longer asme rated for anything. The weld will need to pass x-ray and the vessel hydro’d and recertified which would probably be more expensive and a pita for you unless you have connections to get that done.

Also you need to verify whatever coating you plan to use is applied in the exact manner it is meant to be applied honestly @spdking is correct here. The coating would need to be one designed for pressure as well. A polymer coating meant to be used at atmospheric may decay in a pressure vessel.

I’m not interested in arguing with you, I get it you sell stainless vessels and want to make money so you disinformation folks however you can.

If I was having the tank professionally lined you’d think that they would prep the surface before coating or something🥴

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this is a super convoluted work around for just getting the right tank.
i’d venture to guess the prep and coating is just as much as a proper stainless tank.

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I recommend the new spd7 for all your polymer coating needs!

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This is a hypothetical question anyhow but a company who specializes in lining can make those decisions for me after I provide them with process parameters.

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