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brazing air tank??

Discussion in 'The Hokey Ass Message Board' started by surfcaliforniasurf, May 17, 2009.

  1. surfcaliforniasurf
    Joined: Sep 17, 2007
    Posts: 402

    surfcaliforniasurf
    Member

    I have had an air ride kit on my wagon for about 5 years and the tank finally rusted through a couple weeks ago. It is just a 2 gallon tank I have tucked up under my quarter panel, and it doesn't come with a drain. So I ordered a new tank for $75 from Air Ride and then a friend of my family tells me that he will weld in a bung for a drain valve no problem, and the tank will last me forever. I gave him the tank, he welded in two bungs (I marked 2 spots it would clear the exhaust, and he decided to put two in so I could choose I guess). He told me that he brazed them in when I picked the tank up. I put the tank in, so tonight my wife and I went out in the wagon and low and behold when I came out from dinner the compressor was running. I got under and could hear a leak, and I traced it to 2 of the spots he welded (brazed). What I want to know is: Am I going to have a constant problem with this, or is brazing the proper way to do this? My wife and I take this car everywhere, and I don't want to be a thousand miles from home dealing with this issue.
     
  2. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,109

    scottybaccus
    Member

    It really depends on what pressure you want to keep in the tank. Brazing will reliably hold 50-75 psi, but you will likely have trouble at double that. I would prefer a welded bung.

    Did he braze in the valves, or can they be unscrewed from bungs? If fully removing them and starting over is not an option, it would be feasible to grind back the brass and tig the joint with silicon-bronze. That would be much stronger, but still short of welding with mild steel.
     
    lothiandon1940 likes this.
  3. choppintops
    Joined: Dec 9, 2008
    Posts: 1,460

    choppintops
    BANNED

    They should be welded by someone who knows wtf they are doing. Do it right once, or do it wrong over and over. Your call.
     
  4. while i would have tig welded the bungs on , i would think that brazing if it was done properly would hold up fine. now that it's brazed you will have a hard time getting it cleaned up to weld
     
    rockable likes this.

  5. surfcaliforniasurf
    Joined: Sep 17, 2007
    Posts: 402

    surfcaliforniasurf
    Member

    the valve can be unscrewed from the bung, and the other has just a plug in it. Don't get me wrong, this guy is probably one of the most knowledgeable guys I know and he knows what is he doing, I just want to know if this is going to constantly be leaking?
     
  6. choppintops
    Joined: Dec 9, 2008
    Posts: 1,460

    choppintops
    BANNED

    If he knew what he was doing, it would have been welded and not brazed, and, it wouldn't be leaking. But yes, leaks wont cure themselves, if it leaks now, it will leak forever.
     
  7. surfcaliforniasurf
    Joined: Sep 17, 2007
    Posts: 402

    surfcaliforniasurf
    Member

    Leaks don't fix themselves? Obviously. Tig would have been preferred we all know that, but can brazing done properly last?
     
  8. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,109

    scottybaccus
    Member

    Sure. It takes care and attention to detail. You have 3 options at this point. grind it back and then 1. braze it again, 2. silicon-bronze, 3. weld it. The difference between the 3 is how much prep is necessary and what equipment you have to work with.
     
  9. surfcaliforniasurf
    Joined: Sep 17, 2007
    Posts: 402

    surfcaliforniasurf
    Member

    thanks, now I can go to bed easier, knowing that I am not totally up a creek! Thanks for the input and clarification guys.
     
  10. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,253

    Hackerbilt
    Member

    IF its leaking at the actual joint I would be concerned that the rest of the joint is comprimised. Brazing is pretty much foolproof IF you know how to do it. (No dabbing it in...you let it flow...)
    Truth? Unless you have someone else to do the job I'd just go buy another tank.

    You wanted drains to prevent water buildup...well you'll get no depth of water if you drain regularly, but you'll still have a wet tank AND the paint is burnt off inside around the bungs so you'll most likely have INCREASED rust in those locations.

    I think the best way would be to use a bung on the top of the tank with a siphon tube inside to the bottom low point and a small ball valve in easy access inside the trunk. With an additional tube to the outside of the trunk floor, draining would be easy and clean.
    Water would stay away from the tank bungs as well.
     
  11. bshepherd
    Joined: Apr 16, 2009
    Posts: 130

    bshepherd
    Member
    from michigan

    I prefer to run a moisture trap, they make them specificly for airride suspesions. You can also run the stuff they put in semi air brakes, its alchol based and it gets rid of water. They use in the winter to keep brakes from freezing up in cold climates.Brandon
     
  12. noboD
    Joined: Jan 29, 2004
    Posts: 7,895

    noboD
    Member

    What he said. CLean ALL the braze off if it's going to be tig welded.
     
  13. 61bone
    Joined: Feb 12, 2005
    Posts: 890

    61bone
    Member

    Pinholes in brazing are not uncommon, but they are the result of the prep not being good enough. The bungs can be reheated and removed, cleaned up and rebrazed. If you just have one pinhole, clean it up good and lay a little solder over it.
     
  14. Jersey Meathook
    Joined: Feb 9, 2009
    Posts: 164

    Jersey Meathook
    Member

  15. pasadenahotrod
    Joined: Feb 13, 2007
    Posts: 11,776

    pasadenahotrod
    Member
    from Texas

    That hit the nail right on the head, dead center.
     
  16. krylon32
    Joined: Jan 29, 2006
    Posts: 7,919

    krylon32
    Alliance Vendor
    from Nebraska

    I'm so dam paranoid that I'd get a new tank and start over and use a moisture trap and not weld on the tank at all! No leaks.
     
  17. HRK-hotrods
    Joined: Sep 26, 2007
    Posts: 922

    HRK-hotrods
    Member

    Or you could have bought a used 7 gallon tank from a heavy truck salvage yard for about $40 from a Mack. Oh, the $40 tanks are aluminum... Most of the Mack tanks have 7 ports on them too (5 1/2" ports, 2 3/8" or 1/4") :)
     
  18. johnboy13
    Joined: May 1, 2007
    Posts: 1,073

    johnboy13
    Member

    If the valve is removeable, are you sure that it isn't leaking around the valve? Did you use some kind of thread sealant on it?
     
  19. budd
    Joined: Oct 31, 2006
    Posts: 3,478

    budd
    Member

    braze will work, but how ever you fix it make sure you test it before you use it, soapy water and a little paint brush while it has pressure.
     
  20. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,109

    scottybaccus
    Member

    You are absolutely right and very wrong. That's a neat trick!

    You are right that brazed joints on hvac lines hold a lot of pressure. BUT, the brazing is not the mechanical joint holding the load. It is the seal for joints that are slip fit, one into another.
    The scenario described in this case lacks that slip fit, so the joint is more like a butt joint, the brazing material like a weld fill around the perimeter. It lacks the walls of tubing to reinforce the joint. That alone may hold 250 psi for a time, but the cycle of high and low pressure on the system will eventually cause the joint to fail, unless very lucky. It can be done, but not in the form you Maytag repairmen know.
     
  21. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,964

    Shifty Shifterton
    Member

    Actually what really matters is how it leaks.

    Is it a single pinhole?
    Is it multiple locations?
    Is it a hairline at one end of the braze?

    Brazing is one of those things that can go all kinds of wrong if there's a minor prep or environmental issue. A single pinhole you can probably get away with fixing, but any more ought to have the filler removed and start again.

    We don't know it's a butt joint either (unless I missed something). If I was gonna braze fittings, would be tempted to use threaded fittings in threaded holes.
     
  22. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,957

    gas pumper
    Member

    This is the answer!

    drill tank, tap for 1/4 pipe. install a 1/4 to 1/8 reducer bushing then braze.
    Now you have a mechanical joint and sealed permanantly with braze. or even solder.
     

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