Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by ZippyDDoodah

  1. ZippyDDoodah

    Basic Caesar II / pipe analysis queries - Structural Engineer

    "Most pipe can deflect 1/2 inch in a 20ft span (even considering simple supports) without experiencing any overstress at all, whereas such a deflection in a structural member, even if not overstressed, would cause unsightly cracks in concrete beams" "in general piping is very flexible in...
  2. ZippyDDoodah

    Basic Caesar II / pipe analysis queries - Structural Engineer

    nickelkid, thanks for your response, but I have to ask, what was the extent of the "input/support" from your structural folks? For each seismic and wind load case, did you obtain structural displacements for each of those load cases and then apply them to your piping stress model at each pipe...
  3. ZippyDDoodah

    Basic Caesar II / pipe analysis queries - Structural Engineer

    I'm also a structural engineer. Here are a few important points - pipe stress analyses are almost always nonlinear, so "unfactored" piping loads are unacceptable for structural design since superposition in load combinations is not valid for nonlinear load cases. You must insist that the piping...
  4. ZippyDDoodah

    OPINION ABOUT USE OF SPRING HANGER IN FLARE NOZZLE

    edwin, why not use less expensive non-spring support(s) instead of a spring hanger given that deflection is so small? Significant load redistribution can occur before a pipe fully lifts off a support, so the calculated .1 mm deflection is not necessarily a concern.. Your allowable loading seems...
  5. ZippyDDoodah

    Approach to ASME B31.1/B31.3 code stress calculations

    Typical pipe stress load cases commonly used for ASME B31.1/B31.3 code stress calculations seem mathematically inconsistent for nonlinear analyses (+Y supports, gaps, friction), relying on linear algebraic subtractions when dealing with nonlinear (NL) load cases. Superposition doesn’t apply in...
  6. ZippyDDoodah

    Pipe lift off in dynamic analysis

    Caesar II is capable of nonlinear static analysis if the nonlinearity is limited to boundary conditions. Gaps, friction, and bi-linear springs are all nonlinear boundary conditions which Caesar handles in static analysis. Caesar cannot consider material nonlinear behavior, geometric nonlinear...
  7. ZippyDDoodah

    Pipe lift off in dynamic analysis

    You gave dangerous, incorrect advice to the person who started this thread as has already been explained in detail, whether you care to acknowledge your errors or not. When called out on your misguided advice and wrongheaded understanding of the subject matter, instead of admitting that you...
  8. ZippyDDoodah

    Pipe lift off in dynamic analysis

    That has to qualify as one of the most bizarre comments I've ever read in an eng-tips forum.
  9. ZippyDDoodah

    Pipe lift off in dynamic analysis

    "Since we started and open discussion, can you please explain here where and why you consider uplift supports with gap and friction if you are supposed to run a dynamic analysis?" You seem quite unwilling to read and comprehend. It DOESN'T MATTER whether the analysis is static or dynamic. If...
  10. ZippyDDoodah

    Pipe lift off in dynamic analysis

    "If you read my answers I have never talked about friction or uplift supports with gaps, and the post was not asking for them either. Please do not pull the conversation/discussion into different subjects." Perhaps you missed the title of this post: Pipe lift off in dynamic analysis You...
  11. ZippyDDoodah

    Pipe lift off in dynamic analysis

    "ZippyDDoodah, I guess you generalized the problem on all types supports and too far, however missed the concern was for uplift only" saplanti, by definition, the ability for the piping to "uplift" means that the support is nonlinear, and therefore a nonlinear analysis is required if the...
  12. ZippyDDoodah

    Modelling Pump Nozzles

    Model the pump as a rigid element using the pump weight just as DSB suggested. Support it with +Y supports with a friction factor for concrete (.6 or .7 ??). Model discharge and suction as DSB suggests, because discharge piping will add to the weight for increased friction resistance.
  13. ZippyDDoodah

    Pipe lift off in dynamic analysis

    Actually, DSB's advice was not a "full description" of what to check, but a general word of advice as to what to watch for. If nonlinear supports in the piping system are defined with gaps and friction which is common, dynamic load distribution and reactions cannot be reliably determined with...
  14. ZippyDDoodah

    Another B31.3 Pipe Stress Analysis Question

    Rob, apologies for getting you sidetracked. I think you will get much more from Peng & Peng's book than from Kellogg. In fact, Peng references Kellogg methods often in their book. The B31.3 code has you consider weight and pressure stresses independently from thermal stresses. As you are...
  15. ZippyDDoodah

    Another B31.3 Pipe Stress Analysis Question

    Actually beam element programs, if designed with nonlinear analysis requirements in mind, should be able to handle nonlinear analysis just fine. Not just gaps, friction or multilinear springs either. There's no reason other than limitations with specific software programs as to why beam/line...
See more

Part and Inventory Search

Back
Top