Who said you can't do that???

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I am reviving an old thread about making square air tanks and using the frame rails of your truck as an air tank. I have heard many arguments against it and I forgot I had this magazine article from the July 2007 MiniTruckin' issue. I had to shrink to fit the forum picture size, but if anyone wants it in full size, pm me. Here they use a frame rail to make an air tank and they test it to 200psi!!!!Lincoln Power Mig 210MP MIGLincoln Power Mig 350MP - MIG and Push-PullLincoln TIG 300-300Lincoln Hobby-Weld 110v  Thanks JLAMESCK TIG TORCH, gas diffuser, pyrex cupThermal Dynamics Cutmaster 101My brain
Reply:I think that I remember most saying it wasn't good idea, not that you can't pressurize a welded, steel, boxed section to hold 200psi.  I'm sure it will hold far more than that.  I'm not sure that-The State of CaliforniaDept. of Industrial RelationsDiv. of Safety and HealthPressure Vessel Unitwould certify it....Like they do my air compressor tanks.Hobart 140 Handler w/ gasHyperTherm Powermax 380 Plasmaoxy/acetylene
Reply:This is actually a trick used by some racers to hide a nitrous system. Find something hollow, cap it off, add the right fitting and away you go.My only real concern would be painting/sealing the inside to prevent rust.
Reply:I am a Jeeper and it's common for Jeepers to make bumpers out of 2x5 tube stock that is 3/16 inch thick with the dual purpose of being an air tank. I buy my co2 (not in bumpers) from my welding supplier.... they had never heard of using co2 to air up tires, or to operate air tools. Qualified & experienced at welding scrap metal
Reply:Originally Posted by levelzeroThis is actually a trick used by some racers to hide a nitrous system. Find something hollow, cap it off, add the right fitting and away you go.My only real concern would be painting/sealing the inside to prevent rust.
Reply:Originally Posted by little Jeep I buy my co2 (not in bumpers) from my welding supplier.... they had never heard of using co2 to air up tires, or to operate air tools.
Reply:I think you're right Burnit. I've heard of people using nitrogen their tires.Lincoln AC/DC 225/125 Stick Linde HDA-300 MillerMatic DVI MIG Miller Dynasty 200DX Hypertherm Powermax 1000
Reply:Ive seen people use c02, they even sell kits to turn regular co2 paintball tanks into mini tanks for filling tires and running air toolsI like to party!
Reply:Nitrogen is great... but C02 is good.***************************************Lincoln AC225 stick welderLincoln HD100 WeldPak flux core wire feed welderThree of the cheapest grinders money can buy
Reply:There's a big difference in something like that, with the largest side being 4" across, and a tank that has large, flat sides.  Keep in mind that pressure is measured in pounds PER SQUARE INCH.  If you have a tank that has a side that measures one square inch of surface, it only sees 200psi.  If the side measures 12"x12", that's 144Sq in, which would put 28,800 pounds of pressure on that side (at only 200psi).  Can you see how that might tend to flex a lot more than a 1"x1" cube would?  Can you also see now how the corner welds may tend to fatigue from this flexing?
Reply:Originally Posted by BurnitDo you mean nitrogen? Im definitly not tryin to start an arguement here, but I have worked in motorsports for years and everybody uses nitrogen in there tires because its not as temperature sensitive as air with water vapor, co2 seems like it would be worse. no?We also used bulk nitrogen to run our air tools at the track. Using co2 just seems harder
Reply:Also keep in mind that the testing of pressure vessels usually requires at LEAST an overpressure of 3x.  So testing to 200 psi means the vessel might be rated for 65 psi max use.And like Engloid pointed out, size matters!  A piece of 1/4 inch wall 1 inch square tube can handle pressure much better than 1/4 inch plate 12 x 12 inches.And if one where to have a catastrophic pressure-vessel failure and the pressure-vessel were home made, whose butt would be in the sling?And square shapes or sharp corners are double-plus-ungood AKA BAD-BAD-BAD for pressure vessels!!!  The corner stresses and stress concentrations at those corners are bad.  And those 'good-ole boys' are using a stressed frame member and superimposing the stresses from pressurizing it too?
Reply:CO2 can be extremely corrosive in the presence of moisture.  It forms carbonic acid.  We do a lot of work with CO2 in the oil industry, injecting it into the ground to help get oil out.  Everything has to be stainless.We used to have tubular bumpers on our trucks that were used to store air at 100 PSI.  It can be quite dangerous in an accident!America Needs AMERICA'S Oil!!!"Global warming is the greatest scam in history ...There is no run away climate change. The impact of humans on climate is not catastrophic. Our planet is not in peril."--John Coleman, Founder of The Weather Channel
Reply:Originally Posted by steve45CO2 can be extremely corrosive in the presence of moisture.  It forms carbonic acid.  We do a lot of work with CO2 in the oil industry, injecting it into the ground to help get oil out.  Everything has to be stainless.We used to have tubular bumpers on our trucks that were used to store air at 100 PSI.  It can be quite dangerous in an accident!
Reply:Originally Posted by BurnitDo you mean nitrogen? Im definitly not tryin to start an arguement here, but I have worked in motorsports for years and everybody uses nitrogen in there tires because its not as temperature sensitive as air with water vapor, co2 seems like it would be worse. no?We also used bulk nitrogen to run our air tools at the track. Using co2 just seems harder
Reply:Originally Posted by little JeepI am a Jeeper and it's common for Jeepers to make bumpers out of 2x5 tube stock that is 3/16 inch thick with the dual purpose of being an air tank. I buy my co2 (not in bumpers) from my welding supplier.... they had never heard of using co2 to air up tires, or to operate air tools.
Reply:Is two cubic feet of air at 120 psi equal to 8 cubic feet at 30 psi ?? I guess my real question is, how many usable cubic feet of air you going to get stuffed into a frame or roll bar?
Reply:Originally Posted by seamusOne of the last 4 Wheel and Off Road or JP magazines had an air tank roll bar as a feature story.For off road purposes, CO2 is fine as "accurate" tire pressures aren't a necessity.  I wouldn't use it with a steel wheel though, only aluminum.CO2 doesn't react with aluminum, does it?
Reply:Good.  Then I'm safe.