Guest TegRacer324 Posted July 26, 2006 Share Posted July 26, 2006 Well in my ever going quest to mount a fuel cell in my car I was just wondering how do you prevent mild steel tubing from rusting from the inside out? Weld up the ends? Try to paint it? or do most guys just use stainless for tubing? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 26, 2006 Share Posted July 26, 2006 If you're talking about the frame for the cell, I wouldn't worry about it too much. When I've been welding tubing I just clean off the end of the tube where I'm welding, and the rest of it has a coating on it from the steel mill. Then paint the outside, and whatever little bit of rust is on the inside would take forever to actually get all the way through. What is more of a concern is where you weld the metal to the frame rails. Here you have the frame rail which is not sealed, and when you weld on the tubing you'll burn the primer on the inside of the tube. I've looked at various methods for preventing rust inside the frame, and it seems like 2 keep popping up. I haven't decided if I'm going to do one or both of them. One is to spray something like POR15 or Zero Rust INSIDE the frame rail using a spray gun with a long tip. The other is to spray oil inside the frame rails. Krown rust proofing in Canada does this, and they use a special oil that turns into a grease after it dries. I haven't found the exact oil that I want to use, but I know I'm going to do the oil inside the frame. I might call the Krown dealer in BC and see if they'd sell me a bit of the oil. I'm still not sure if I'm going to do the Zero Rust inside the frame because I think it's pretty much impossible to get full coverage. Not sure if getting it as good as I could would be sufficient or if I should just rely on the oil alone. Quote Link to comment Share on other sites More sharing options...
johnc Posted July 26, 2006 Share Posted July 26, 2006 I spray the inside of tubes, replacement panels, etc. with 3M Weld- Thru Coating part number 051131-05913. Quote Link to comment Share on other sites More sharing options...
Guest TegRacer324 Posted July 28, 2006 Share Posted July 28, 2006 Alright thanks guys. John where do you buy that stuff? Automotive or welding store? or even autobody? Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted July 28, 2006 Share Posted July 28, 2006 In order for tubing to rust from the inside out it has to have water or some kind of moisture inside the tube when it's enclosed or it has to have a hole in it somewhere where moisture can get inside it. Properly welded tube frames almost never experience that. Even dune buggy frames don't have that problem. I had a chenoweth dune buggy frame from the 70's back in 1995 and I had no problems with it and it went through the rio grande so many times it wasn't funny. Quote Link to comment Share on other sites More sharing options...
johnc Posted July 28, 2006 Share Posted July 28, 2006 In order for tubing to rust from the inside out it has to have water or some kind of moisture inside the tube when it's enclosed or it has to have a hole in it somewhere where moisture can get inside it. Most do have some moisture inside when welded. What keeps them from rusting out is, in a sealed environement, the oxygen gets depleted quickly after the inside gets a coating of surface rust. No more oxygen, no more iron oxide. the 3M coating is avaialbe at automotive paint supply stores and its expensive. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted July 28, 2006 Share Posted July 28, 2006 Well, that depends on where you live. Here it's so dry that that doesn't happen, and your correct that there isn't enough oxygen inside a completely welded tube to rust through. Quote Link to comment Share on other sites More sharing options...
Twoeightnine Posted July 28, 2006 Share Posted July 28, 2006 When I was working in the eighties for a company called Classic Aircraft. The aircraft that we were building was of the tubing, bulkhead and fabric. The fuselage main structure is molly tubing. If one didn't know and saw one stripped, you would think it was an antennae tower. A braced tube structure. During welding the mech will drill a hole to any tube that will cause closer of the adjacent tube assembly. When comeplete, the fusalage assembly is placed on a stand and pumped with linseed and rotated. It is then drained and a weld bead plaed at the entry and exit holes. I didn't engineer the process but it was part of the Blue Print. Quote Link to comment Share on other sites More sharing options...
Guest TegRacer324 Posted July 30, 2006 Share Posted July 30, 2006 Alright thanks for the help guys. I'll have to go look around for that stuff. Quote Link to comment Share on other sites More sharing options...
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