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Water hammer in annular

  1. Dec 24, 2009 #1
    IN MY WORK a jacketed pipe was damaged i duno whts the reason but i doubt the water hammer
    can any one help me about the analysis of water hammer in jackets
     
  2. jcsd
  3. Dec 24, 2009 #2

    FredGarvin

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    Do you have a fast acting valve upstream of where the pipe failed?
     
  4. Dec 24, 2009 #3
    yes the pipe is 6 meters with 3 mm thickness and 1st tube is 6" dia and the outter tube is 8" dia,eter ,, and the fluid between pipes is coolin water under 4 bars how can it be a water hmmer ??
     
  5. Dec 26, 2009 #4
    holla guys help meeeeeeeeeee in this problem
     
  6. Dec 26, 2009 #5

    FredGarvin

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    Ask a question that means something and perhaps you will get some more help. From your previous answer I can not tell if you have a fast acting valve upstream. Do you? That is the cause of water hammer in most cases.
     
  7. Dec 28, 2009 #6
    yes we have this fast actin valve but how can i make the water hammer analysis in the annular ????????? can u tell me the required equation ?? and how can i make an equivelent pipe for the annular to ease the calculation ??
     
  8. Dec 28, 2009 #7

    FredGarvin

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    All right. I have a pretty good paper somewhere that covers water hammer in space craft systems. It should be applicable. Let me see what I can dig up.

    EDIT: I can't post the paper here because it is copyrighted. However the particulars are:
    Waterhammer in a Spacecraft Propellant Feed System Journal of Propulsion and Power, Vol 8 No.3, May-June 1992.
    I would recommend getting a copy of it for yourself. It is not that expensive.
     
    Last edited: Dec 28, 2009
  9. Dec 30, 2009 #8
    I Dont know but if u can tell me about the maximum pressure wave value for the hammer pressure in my annular ??
     
  10. Dec 30, 2009 #9
    maxx_payne,

    Here is an on-line calculator for water hammer;

    http://www.lmnoeng.com/WaterHammer/WaterHammer.htm

    In your case, the value of A (Pipe cross-sectional area) will be the annulus area and the value of f (Darcy-Weisbach friction factor) should be adjusted to recognize that two (2) surfaces are presented to the flowing fluid... the interior of the jacket and the exterior of the process pipe. Other adjustments may need to be made due to your special situation.

    If you doubt that water hammer is the cause of the damage, what other mode do you suspect?

    I can imagine a case where the inside process pipe could be damaged through design or operational error if;
    1. The process fluid is in the vapor phase
    2. The jacket fluid is cooling water
    3. The process pipe is isolated for a length of time sufficient for the process fluid to condense
    4. The process pipe is underdesigned such that it cannot withstand the resulting differential pressure and therefore collapses.

    On the other hand, if water hammer is the culprit and the valve is motor operated, then the rate of closure can be decreased or if it is a control valve, the manufacturer might have an alternative trim which would solve the problem, see;

    http://www.engineeringtoolbox.com/control-valves-flow-characteristics-d_485.html
    .
     
  11. Dec 30, 2009 #10

    stewartcs

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    If you doubt it was due to the water hammer effect, why do you want to analysis water hammer effects?

    How exactly did the pipe fail? This will provide more insight as to what the failure mode was.

    CS
     
  12. Jan 2, 2010 #11
    1st the inner pipe was collabsed as if u can imagine its cross section became as an 8 approximately ,, and the failure was only in the jacketed parts
    frankly i have to reason to think about
    1- water hammer
    2- thermal stresses ??
    so i need the analysis of the water hammer to find out the solution for this problem
     
  13. Jan 2, 2010 #12
    1st the inner pipe was collabsed as if u can imagine its cross section became as an 8 approximately ,, and the failure was only in the jacketed parts
    frankly i have to reason to think about
    1- water hammer
    2- thermal stresses ??
    so i need the analysis of the water hammer to find out the solution for this problem
     
  14. Jan 3, 2010 #13

    Danger

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    I'm the least qualified to answer here, but there are a couple of things that I should mention. One is that most (not all) of us have English as a first language, so your postings are a bit hard to follow. Secondly, although you mentioned the dimensional specifications of your pipes, you didn't say what they're made of. There'll be one honking big difference between aluminum and 1812 stainless steel.
    Past that, I leave it to the experts.
     
  15. Jan 3, 2010 #14
    well am sorry for my bad english , the pipe is made of stainless steel 304
    with thickness 3 mm and length of 6 meters
     
  16. Jan 3, 2010 #15

    Danger

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    In fact, having seen your posting in a (currently) following thread (How to...?)
    You don't seen to have trouble with English when you apply yourself. :smile:
     
  17. Jan 3, 2010 #16
    where is the comment about the main problem of the analysis of the water hammer inside the annular ????
     
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