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Pipe Bend Stress Analysis

  1. Apr 12, 2010 #1
    Hi, I'm trying to calculate the max (von Mises) stress in a 90o pipe bend. Now I know (I think) how to do it for a straight pipe, but can anyone point me in the right direction as to where I can find this analysis for a pipe bend?

    Thanks in advance.
     
  2. jcsd
  3. Apr 12, 2010 #2

    minger

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    Given what loads?
     
  4. Apr 13, 2010 #3
    The internal pressure is around 4 bar.
     
  5. Apr 13, 2010 #4

    minger

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    Have you taken a look for any analytical/empirical solutions such as in the Roark handbook for stress and strain?

    I doubt there is a solution for your exact pipe bend, but I know there are solutions for simple shells of revolution under internal pressure. Perhaps you can adjust the solution for the bend.
     
  6. Apr 13, 2010 #5
    That's pretty much what I'm looking for minger. Roark's handbook you say, do you know any other books with a similar analysis? Thanks for your help so far.
     
  7. Apr 13, 2010 #6
    Don't forget that if your pipe fitting is under pressure, presumabably there is also fluid flowing. This exerts a thrust on the pipeline, which resists in bending, unless there is a suitably placed thrust block, in which case there is a direct force on the fitting.

    Look in any standard hydraulics or fluids testbook for thrust block design.

    Obviously it will make a difference whether the pipe is horizontal or vertical so the question 'what loads' remains open.
     
  8. Apr 13, 2010 #7
    Well, it's just a theoretical question. I need to find the maximum theoretical stress in the 90o pipe bend under 4 bar internal pressure. It's a static analysis I'm doing so there's no need to consider thrust or anything like that. I do appreciate your reply though.
     
  9. Apr 14, 2010 #8
    In my opinion, forces from the flow exerted on the pipes are too often ignored or not taught.

    I have seen really serious consequences ensue as a result of inadequate thrust block provision.

    I have also seen serious damage ensue from neglect of bouyancy, self weight or support forces in soft goround.
     
  10. Apr 14, 2010 #9
    I don't doubt what you're saying but I just need to calculate the max von Mises stress in the bend. Just assume there is no flow.
     
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