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Stainless muffler cracking on muffler of a chiller.

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  • Stainless muffler cracking on muffler of a chiller.

    Okay guy's heres the deal.

    I'm working in a third floor basement ( Yup this building has 3 floors to its basement, I'm 30' below ground )

    They have a 8 cylinder engine that runs off natural gas that is used to run the chiller for air conditioning.

    When I went to look at the job they had a cover patching a hole in the muffler, they removed it prior to me getting there to look at the job.

    So I looked up and seen where it had rusted through leading me to believe it was regular steel, so we rolled up a patch for the 12-1/4" diameter muffler that went 1/2 way around the pipe x 28" long.

    However, Prior to starting to weld I verified with a magnet to make sure it was steel just to discover it was stainless.

    So I then go back to the shop and roll some stainless that goes way outside the damaged area and weld it in and it welds up beautifull, until it cracks from the edge of the weld into the old.

    ( Now I've repaired stainless steam tables that burn out because they forget to keep water in them and the flame just cooks a hole which turns the stainless black and makes it unable to weld )

    Thats not the case here the stainless is not blackened.

    I have 2 choices left, Fabricate a new muffler or put a patch on the top side to match the one on the bottom and then all I have to worry about is wheather it will crack at each end.

    Keep in mind this exhaust ties into several others and is well over 100' long.

  • #2
    Take some pictures n put em up


    • #3
      They typically use 314 series stainless for high heat conditions. 314 is. 25% cr. 20% ni 1.8% si. What did u use to patch it


      • #4
        We used 304 to do the repair, Its not cracking at our weld, Its cracking going away from the the weld and away from our patch.

        The same way steam tables do.


        • #5
          Going from bad memory here.... I hope I'm not giving wrong information..... but if I'm remember correctly I read austenitic non magnetic SS needs a rod that has more chrome in it to over come phosphorus and sulfer that cause the hot cracking in austenitic SS. Also the article suggested using the lowest heat possible, keeping a tight arc and stitch weld to keep the weld pool as cool as possible. A ferritic SS rod has more chrome in it.

          Here I found the article, look at the bottom of page 7. Hot cracking

          This rod chart might help.

          Last edited by tackit; 04-18-2013, 06:02 AM.