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Stainless TIG brazing with nickel rod

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  • Stainless TIG brazing with nickel rod

    I need to braze a tank from light gauge stainless and thought I might braze it with nickel rod to better guard against blowing holes. What type of nickel rod is appropriate for this? Is Type 82 OK? Is a nickel-brazed joint on stainless discernible from the parent metal (304 stainless)?

    Thanks in advance.

  • #2
    Hey SuperMatty. What cha building?
    I'm curious bud...tank...light gauge stainless? Sounds like a flux capacitor or possibly a still?

    Not that it matters but sometimes knowing about the fabrication, it's construction, goes along way to a more suitable, professional answer when trying to offer an opinion.
    But to prove I'm not a professional...I was lost at your references to type 82 and brazing.

    I know now your referring to an Inconel filler metal. (ERNiCr-3) Thank you Google.
    You also mention brazing? I could well be mistaken but type 82 isn't a brazing rod? (RB CuZn-D)
    The difference the later being a metallic bond, the former a bond of fusion through dilution.

    However, Stainless... thin and the risk of burn through. Hmm?

    At the risk of sounding dimmer then I appear, if you asked me to remove your gull bladder I'd say sure, I can cut you open with the sharp lid from a tin can, a box cutter or a scalpel. All will do the job, but the quality of the cut will differ.

    I'm assuming you plan on GTAW your stainless. Again with no clue what your fabricating or it's joint design.
    While using an Inconel filler may offer an easier time welding, sluggish is more forgiving, maybe...sometimes to avoid burn through issues you should look at the process and ask what you should do to adapt it to your application?

    Tungsten size, profile, cup size...using chill strips and changing joint design. All and more make welding thin stainless easier. Big one's are tungsten profile, amperage, arc length, inclination and travel speed. Maybe the welding can be done autogenously if the design was changed?
    And while more experience allows for less concern for these variations, they are the foundations to first address with welding concerns.
    But you mention discernable from the parent metal. Brazing of any kind will be. Using Inconel, slightly. More so depending on whether it's dome with the lid, box cutter or scalpel.
    Probably not much help but the price was free. Good luck in your endeavors.

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    • #3
      Additionally, knowing what's going to be in it may help. Is this going to hold food grade materials? Fuel? Mild chemicals? Potable water? Non-potable water? Cursed Meso-Amercan artifacts ? The closer you can get to the chemical formula of the parent metal, the stronger the joint.
      ____________________________________________

      I don't need to find myself. I'm always at my lathe.

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      • #4
        I think I was mistaken when I posted initially about using nickel rod for brazing. It appears that the nickel rods I was thinking of will melt at approximately the same temperature as stainless steel, so it would be more of a welding joint, rather than a brazed joint as I had hoped.

        I'm going to try 94/6 tin/silver solder instead.

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        • #5
          Silvalloy 355 is a good choice. Just as strong as brazing. Hope everything goes OK.
          ____________________________________________

          I don't need to find myself. I'm always at my lathe.

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          • #6
            Originally posted by buffumjr View Post
            Silvalloy 355 is a good choice. Just as strong as brazing. Hope everything goes OK.
            Actually that is a brazing alloy, 56% silver
            Richard

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            • #7
              I once did some stainless GTAW tube work for a guy who was building something secret.
              Some kind of fuel atomizer, going to change the world...
              I was like good, you can afford $65 an hour with all the money you'll be saving in the future.

              My buddy brings over this electrical device...needs a little solder on "this" wire. He left it with me. He just didn't think I'd put a battery in it to discover it vibrates and wiggles.

              I'm sure your secret is worth keeping, but... to use a silver brazing alloy to join your stainless...oh buddy? Forgive my lack of tact but what are you building and what are you thinking?
              I like others have a very limited picture of what your trying to build, a tank. If experience counts for anything, heed the advice that's been given son, we do want to help, give us something to use.

              Yes...you can join SS with brazing Alloys. However...depending on what, how it's designed, the equipment and consumables used, as well a small degree of understanding of the basics of metallurgical bonding, my advice would be stop and ask more questions and provide more details.

              One thing for sure, when you factor in the cost of the BAg alloy, the flux, the fuel gases, prep, set up, fit up and clean up...you'll probably get away cheaper finding a good welder with GTAW equipment but who's to say.

              If you don't find a lack of color match an issue you could probably just use the RB CuZn-D.
              It has a bit of nickel in it? Added strength go figure?

              One last thing..
              .You understand you'll be doing this with a oxy fuel torch? Well SS
              is a finicky material to braze. It's finicky because most over heat it and the brazing alloy. For that reason, my final advice with little too go on...practice.

              Learn solidus and liquidises of the product. How to recognize the clues the products use offers, and finally, how to control the application of heat to maintain it. And if things go south on you, well...that's how we get educated.

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              • #8
                It's just a tank to hold about 1 gallon of hot water. No big deal. I want to be able to file a perfectly smooth finish that appears monolithic, rather than having the appearance of being welded together. The metal is only about ~0.04" thick, so I might try using a small pencil-tip type propane torch initially. The solder will melt at around 450 or so, so it won't take much. (Stay Brite #8)

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                • #9
                  Well...guess I do have more to say?
                  Just so you know, AWS defines anything with a melting point below 840 degrees F as a solder, above as a brazing filler metal. Your hoping to solder. Cool. A lapped seam will be a better choice for fit up, and a tight fit up. will hold the parts together while you try to fill the seams.
                  Trying to solder a square edged corner joint... a heck of a lot harder. But don't take my word for it?
                  Try it and see...it will be harder. I look forward to the pictures.

                  Any how, four rules to follow.
                  1) Clean- remove oils greases paint oxides depending on material types.
                  2) Prepare- chamfered edges, cross hatching, all increases surface area for increased bond strength.
                  3) Flux- Compatible flux to the filler. Flux plenty, It will remove residual oxides, act as a protective barrier to prevent oxidation, a lubricant and also a noticeable temperature indicator.
                  4) Control heat input- Most as I previously mention screw things up because they can't judge heat input. That Stay Bright #8 has a window of 480 solidus and 535 F liquidus. Your pencil torch will produce a higher flame temperature but questionable on volume.

                  Point being, you get it to hot and your burning it. After that, things will be ugly. To make matters worse, it won't be an easy mess to fix.
                  I should mention... .04, that's pretty thin.
                  While I'm a good welder, and maybe sometimes to smart for my own good, if it's just holding water, do you self a favor, check out panel adhesives.
                  I'm giving you a solid when I say, I've given you my best advice with the information I've been given.
                  Good luck.

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                  • #10
                    Are you assembling this from sheet metal? What sort of fittings? Patching a hole? What all is going on there?

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