How to seal Air tank?

[bagged69chevy]

I made a custom Air tank and have a few pin holes in it. I plan on welding the pin holes up but am worried because i have quite a few seams/welds I'm worried will degrade over time due to moisture and fatigue. Is there a coating i can coat the inside of the tank with that will help protect the welds form the inside; and possibly seal up microscopic pin holes?

Ive heard some guys talking about gas tank sealants but didn't know if that would work for air tanks under 150-200psi pressures.

also.. the tank is the back half or my frame.. so thoughts on that as well. Has that be done successfully? (keep in mind this is not a daily driver, but will be driven from time to time)

And not to be a jerk, I know guys like to give their opinion even though they have no first hand knowledge on the subject. Im looking for informed opinions on the topic; this is going to be a sema truck and want to make sure its done right the first time. We have spent countless hours making the frame work as an air tank and really want to make it work if possible. Holding safety and functionality above everything.

Thanks guys

[tonypaul]

I know your looking for solid opinions but I realy dont thing there is any kind of sealer that your gonna find that will withstand the pressures needed for a airbag system. I suggest getting a real airtank designed for this type of application. Check on ebay there pretty cheap...

[AVS_JASON]

Frame tanks have been done countless times, with no problems. As long as you trust your welds, then you should have very few problems. Just don't drag it too much.

[875.3CHEVY]

i used eastwoods internal frame coating on a 55 chevy were building worked good.they also make a sealer but i think thats paint talk sealer not plug a hole sealer.also i would put a petcock in front and behind the axle hump.http://www.eastwood.com/internal-fra...ay-nozzle.html
http://www.eastwood.com/eastwood-s-f...-deadener.html

[Shane]

Personally I wouldn't rely on a chemical coating to seal for leaks. Pressure vessels are nothing to mess around with and I only say that from a saftey standpoint.

I would pressurize and located the pinhole leaks (soapy water method) and re-weld those areas.

[kev2809]

^^^ agree. grind them down and weld up the holes. unless maybe some metal to metal filler?
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[jasonhall]

Any pics of the frame?

[bagged69chevy]

I have checked the entire frame for pin holes.. Ive filled probably 40 or 50 tiny pin holes. My worry isnt finding all the pin holes and welding them up. Thats done; my worry is new pin holes appearing in the future due to stress and fatigue on the frame, and possible rust deteriorating the welds from the inside. I was hoping to somehow seal interior surfaces of the frame with a coating to help prevent future pin holes from surfacing.

[bagged69chevy]

Originally Posted by AVS_JASON

Frame tanks have been done countless times, with no problems. As long as you trust your welds, then you should have very few problems. Just don't drag it too much.

Did you guys ever seal the inside of the frame, or just leave it bare metal?

[gringoloco]

You are smart to want to seal the inside of the frame. As the compressed air enters the frame from the lines, it will expand, causing cooling and condensation. This water will eventually cause rust which will eat away at the inside of the frame, welds first. Might be years down the road, but better safe than sorry...

Any rust preventative sealer should work, the trick will be getting it to coat the area entirely- would be nice to have the frame on a rotisserie to 'slosh' the sealer around, covering all areas. I think a fuel cell sealer would be a good place to start.

[cajundragger]

I wouldn't put anything inside the frame except having it e-coated.

[bagged69chevy]

Originally Posted by cajundragger

I wouldn't put anything inside the frame except having it e-coated.

What is an e-coating? Where can I get that done?
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[cajundragger]

e-coat is the stuff that new parts come shipped with. Its a black "primer" that is electrically applied to metal to coat it. Its real uniform and will get in every crack and crevice since the parts are dipped and completely sumerged in it.

In Jackson MS. there is a place that has teamed up with the Titan plant and offers e-coat, you'd have to figure out where in your neck of the woods you can get it done.

[lakeroadster]

My "day job" since the early 1980's has been designing pressure vessels. If you need an air tank, buy one. And when you buy the tank make sure it is built to the ASME code and that it has a "U" stamp on it.

Ever seen an air tank that has exploded? Scary stuff:

http://www.doli.state.mn.us/ccld/Boi...identsAir2.asp

http://www.doli.state.mn.us/CCLD/Boi...identsAir3.asp

http://www.dli.mn.gov/ccld/BoilerIncidentsAir1.asp

http://www.asme.org/Codes/CertifAccr...ure_Vessel.cfm

[baggedout81]

I'd deff. run some kinda water or coalescing trap before air inters frame

[Shane]

Originally Posted by lakeroadster

My "day job" since the early 1980's has been designing pressure vessels. If you need an air tank, buy one. And when you buy the tank make sure it is built to the ASME code and that it has a "U" stamp on it.

Ever seen an air tank that has exploded? Scary stuff:

Best advice this thread has seen yet.