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Thread: Tank stud dogbone repair help

  1. #1
    Join Date
    Aug 2010
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    San Diego, CA
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    123

    Default Tank stud dogbone repair help

    I removed old studs from tank half's and noticed on one tank that someone had previously over tightened it through to inside of tank. That stud was difficult to remove so possibly was epoxied in or strong locktight. At any rate I'm hoping someone has come across this before and could recommend a good way to repair. I'm thinking of two possible fixes, weld the new stud in place or use JB weld on threads and screw in. Not sure what that piece in the tank is actually called so I'll call it a dog bone. Does anyone know if the tanks and that piece are brazed? If brazed than welding might yield to much heat and cause the brazed area to fail. JB weld is suppose to be impervious to gas, any thoughts on this. I realize that either repair will make the stud un-removable but don't see that as a concern.
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  2. #2
    Join Date
    Aug 2004
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    Beautiful Northern New Mexico
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    The tanks are gas welded together, including all fittings, no brazing. That stud is not the right type for there so easy too see it could screw it up. The only real way to repair it is to dismantle the tank. Everything else is just a band aid and will fail eventually. Welding in the stud would be the last resort, the welding will make the stud fail sooner than later.
    Robbie Knight Amca #2736

  3. #3
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    Aug 2010
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    San Diego, CA
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    Certainly don't want anything to fail in the near future. What do you mean by dismantling the tank? Are you talking about completely removing the welded back of tank, that seems pretty extreme. Also I'm not equipped nor experienced in any type welding so would need this done by a shop. Appreciate any further details on how to properly repair?

  4. #4
    Join Date
    May 2009
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    175

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    Silver braze with a high silver content ought to do it. The welder will be able to tell whether the braze is sucking into he joint. If for some reason that doesn't work, the "dogbone" can be cut out with a hole saw and a new one welded in.

  5. #5
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    Aug 2010
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    San Diego, CA
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    Considering silver braze. I've also been trying to locate a possible replacement for what I think is actually called a blind hole bung. The OEM thread for this bung is 5/16x24 but the closest I can find is 5/16x18. Also does anyone know if these bungs are the top-hat style bung? Perhaps some grinding might reveal this but before I decide on this route I would like to have a suitable replacement in hand. Does anyone know where to purchase a replacement bung 24 threads or am I o/k using 18 thread bung? I could also buy a top hat 1/4x20 threaded bung and retap to 24 thread. So, top-hat style or not, 5/16 18 thread or get 1/4x20 and retap?
    Last edited by lrcormier; 09-05-2020 at 08:40 PM.

  6. #6
    Join Date
    Jan 2006
    Location
    Menomonie, WI
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    Years ago I did a few repairs like this and I made them. Any oddball threads I ordered a tap from MSC.

    Jerry


    Quote Originally Posted by lrcormier View Post
    Considering silver braze. I've also been trying to locate a possible replacement for what I think is actually called a blind hole bung. The OEM thread for this bung is 5/16x24 but the closest I can find is 5/16x18. Also does anyone know if these bungs are the top-hat style bung? Perhaps some grinding might reveal this but before I decide on this route I would like to have a suitable replacement in hand. Does anyone know where to purchase a replacement bung 24 threads or am I o/k using 18 thread bung? I could also buy a top hat 1/4x20 threaded bung and retap to 24 thread. So, top-hat style or not, 5/16 18 thread or get 1/4x20 and retap?

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