Weld integrity

Discussion in 'Metal Boat Building' started by SilverMack, Sep 9, 2014.

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  1. TANSL
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    TANSL Senior Member

    The OP is not asking you how to weld. The only question is : How do you check your MIG welds for strength and non porosity? (Non destructive of course)
    Probably also the tests that need to be done to check the quality of a weld is the same, irrespective of the metal. To check the strength of a welding (which is not the same as quality) you need to do a test piece of certain properties, and submit it to the appropriate mechanical tests.
     
  2. Mikeemc
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    Mikeemc Junior Member

    Maybe this will work for you. You will need a very strong neodenium magnet and some fine iron filings. Put the magnet on the back of the weld and the filings on the other side to be tested. Remove the magnet and the filings will fall off , the ones that stay are stuck in micro holes in the weld.
     
  3. gonzo
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    gonzo Senior Member

    Testing a sample does nothing to assure the boat is welded properly. It only sets a baseline to establish SOPs.
     
  4. Dutch Peter
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    Dutch Peter Senior Member

    Silver Mack,


    Strenght of a weld is not tested but 'assured' by the following measures:


    - Weld design (e.g. length, throat thickness, strength calculation)
    - Welding procedure (proof that the methode used is good)
    - Welder qualification (proof that the welder can actually weld)
    - Non destructive examination on the weld (make sure the weld is not flawed)


    Above will not give you 100% certainty, but is accepted worldwide as being sufficiently assuring.


    On the issue of porosity:


    This can be found by means of x-ray or ultrasonic examination and, if on the surface, by visual, dye or magnetical examination.
    It very much depends on the Welding Code used, how much porosity is acceptable.


    Hope this helps.
     
  5. TANSL
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    TANSL Senior Member

    Of course not. You can weld very well the area that you are going to check and leaving the rest of the boat without welding. I´d recommend stop saying the obvious.
     
  6. gonzo
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    gonzo Senior Member

    Insults are not a positive contribution to the forum. You need to adjust your bad attitude and refrain from so much negativity.
     
  7. TANSL
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    TANSL Senior Member

    I think I'm absolutely positive when I say that your comment is obvious. I try to eliminate what is useless.
    In some cases it must be checked 100% of the welds, for example, when liquefied gas vessels are built. Typically a sampling of welds, so that the results can be generalized to the entire hull.
    In any case, porosity, lack of penetration, weld not centered, ... are detected by means of non-destructive methods. Procedures to determine the resistance of a weld are totally different. The post of Dutch Peter talks about what I do. I think these are the positive attitudes that basically try to answer the questions with precision. Say what everyone knows, that a test does not prove that the world is correct or not is neither positive nor negative, is neutral, is useless.
     
  8. gonzo
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    gonzo Senior Member

    By your standards of saying what other people already know, all your posts are useless. That is, unless you are publishing original research. You are simply being obnoxious and insulting.
     
  9. TANSL
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    TANSL Senior Member

    Gonzo, at no time have tried to insult. I can assure you that I feel for you all the respect you deserve. Be happy. Cheers.
     
  10. gonzo
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    gonzo Senior Member

    Your statement is that answering questions is useless. Then, as you have done in other threads, claim ignorance or lie about your insults.
     

  11. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    Since it appears this September thread has gone off track a bit and is turning into more jabbing than productive discussion, it is being closed at this point. Hopefully the responses as a whole were useful to the OP since he hasn't posted a followup question in the thread. If someone finds someone else's posts are usually annoying rather than useful, please click their username and select "add to ignore list" so that you are not bothered by their posts. Thanks.
     
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