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  • 304 ss problems

    I have been fixing a tank and the only thing I can come up with is the tank had caustic in it for years and I think that has taken a toll on the 304. Not only that but the 10,000 gal tank was droped on the bottom flange, the ss was cracked like a spider web around the flange I have never seen stainless rip like this.

    I have cut out the old flange and tried to get all the cracks out and have welded a new flange and patch back into place and the stainless just keeps cracking as you weld. I am thinking that the only fix to this is to just junk the tank I just wanted some other ideas cause this is a very expensive choice for the company to make.

    I welded a test pc for the company to look at before I placed the new flange in the tank. What I did was what i cut out I welded onto new 304 ss just like the new patch was going to be made out of and in one good hit with a hammer it cracked look at the photo.
    Attached Files

  • #2
    You might get more responses to this question at the AWS.ORG website. There are some pretty advanced stainless metallurgists who post there all the time. Use the search forum function to find the threads on stainless craking. They have probably discussed a problem like yours already. If not, you could post a new question. It really depends on a lot of variables in your process. We weld a lot of 304 stainless here and have never had cracking issues - except on thin highly restrained fillet welds, which we solved by using a 312 filler wire.

    Here is what the search at AWS found for posts on stainless cracking:
    http://www.aws.org/cgi-bin/mwf/forum...ime&order=desc

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    • #3
      Thanks I will look there and see what I can find

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      • #4
        I would say that the tank is toast, over the years I have had situations like that, usually its a chemical tank, such as clorine, caustic, brine etc.
        Once it starts it will keep going. I have worked on CIP tanks (clean in place) and had them crack around the outlet fittings ever couple of weeks, others last for years and nothing happens to them.
        most tanks are 316 ss. If you can weld it and hit it with a hammer and it cracks a good distance from the weld, the steel is no good.
        I am not a metalurgist but I have seen a lot of this over the years, we had lots of trouble with the brine used for cooling the tanks, I had over 200 patches in one before they replaced it. Others will last 40 years and nothing happens to them.
        Milk silo outlet valves on some of our silos cracked regularly, others never do. I think it has to do with the composition of the stainless used in construction.

        Again I am no metalurgist..........

        I know tanks are expensive but that one is toast.....

        Our caustic and cleaning chemical tanks were replaced with plastic tanks and fibercast lines to stop the problem. Brine lines to the presses were replaced with the fibercast also, they changed the plates to titanium at $20000.00 a pop. The FDA made them take an additive out of the brine that kept it from eating at the stainless.......
        Then you have the foreign stainless problems.....

        some of this may help you I hope..

        mike sr
        mike sr

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        • #5
          I am on the same path as you are on this one. Thanks for the info I am sure
          they will like the news I am sure I will have to give them!: I have also posted it on the AWS website to see what the Metallurgy people will say.

          Thanks
          ct

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          • #6
            Originally posted by ct5 View Post
            I am on the same path as you are on this one. Thanks for the info I am sure
            they will like the news I am sure I will have to give them!: I have also posted it on the AWS website to see what the Metallurgy people will say.

            Thanks
            ct
            Youre welcome sir, I hope some of it is useful to you..

            mike sr
            mike sr

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