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  1. Robster1us

    Reduction in MDMT Using Stress Ratios

    I am attempting to perform a calculation for reduction of MDMT in non-impact-tested material in a piping system, and need to understand the stress ratio referred-to in Figure 523.2.2 of B31.5 (or the analogous section of B31.3). My main point of confusion is with the meaning of the provisions...
  2. Robster1us

    CAEPipe Manufacturer now performing engineering services?

    Has anyone received an email from SST Systems saying that they are now performing engineering services in the US? Has anyone heard of software manufacturers also being competitors with their customers in this way? Would appreciate any thoughts or comments on the subject.
  3. Robster1us

    Boiler Controls, Europe and USA

    Hello all. I am looking to make sense of implementing EN 12953-9 and EN 12952-11 (they have essentially the same requirements with regard to my application). I am in the US but trying to produce a design that's applicable to both Europe and the USA for my safety systems for a hot water boiler...
  4. Robster1us

    Support Friction and Contraction Loops, Chilled/Refrigeration Piping

    Thanks BigInch. I think those are great points. "Bowing would tend to distribute the lateral displacements along the pipe, rather than at the loop itself, which is why guides are used to direct the pipe expansion towards a loop without allowing much lateral displacement during the process."...
  5. Robster1us

    Support Friction and Contraction Loops, Chilled/Refrigeration Piping

    Hello all, back again with a piping thermal movement question. If I think about how a pipe might move in the thermal case of a long straight pipe between (2) anchors, with a loop to take up movement, when pipe is expanding and is resting on supports that are not frictionless, the friction...
  6. Robster1us

    Interpretation of MW Kellogg Method Examples

    After long study of the MW Kellogg methods, and setup of the various form (which lend themselves to spreadsheets quite nicely), I have a much better understanding of how to get at least some result for simple systems with the constraints shown in the book (two places only, although I'm working...
  7. Robster1us

    Applicability of the M.W. Kellogg Methods

    joabjim, That, I can certainly help you with. You're right, the book doesn't do a great job of explaining this, and I haven't tried to solve it the way they use (which was all they had 55 years ago). However, the easy way is this: 1. Calculate your shape coefficients, per the method. 2. Set...
  8. Robster1us

    Applicability of the M.W. Kellogg Methods

    BigInch, thanks for helping me understand what you were saying. You always provide well-thought-out responses, and I just wish you were accessible as a mentor on this subject. You should consider pipe stress tutoring after school to make some beer money.
  9. Robster1us

    Is cracking pressure a pressure drop?

    Not that it really matters at this point, zdas, but I was talking about spring checks, since that's mostly what I use. I would agree that other designs may require no dP to keep them open. I suppose I should be specific. I guess we should all try harder at that.
  10. Robster1us

    Applicability of the M.W. Kellogg Methods

    I'm not sure I follow the gist of the comment. However, again, for non-critical service, at low temperatures (below 400°F), and relatively low pressures (and probably some higher pressures too), it seems unreasonable to dismiss the Kellogg method as useless just because a multi-billion dollar...
  11. Robster1us

    Applicability of the M.W. Kellogg Methods

    OK, fair enough. If I look at B31.5, it appears to be based on the same principles as B31.3, and the Kellogg method, and actually talks about expansion stress in the exact same way. The only clue it gives that it may actually mean pipe contraction is that it gives negative e values in Table...
  12. Robster1us

    Applicability of the M.W. Kellogg Methods

    Sorry, BigInch, I'm not sure which question you're responding to, the general applicability of the Kellog method or its applicability to pipes cooling down rather than heating up. If it's the latter, are you saying it's not necessarily OK to use the method as if the cold temperature were...
  13. Robster1us

    Applicability of the M.W. Kellogg Methods

    Thanks Colonel for that excellent reply. I understand that, for large systems, the Kellogg method would be cumbersome, although looking at the people I know who have licenses for pipe stress analysis software, I'm beginning to understand more and more that they don't know that they're doing. I...
  14. Robster1us

    Is cracking pressure a pressure drop?

    An additional note (forgive me if I'm stating the obvious) is that if for some reason, flow drops off such that the pressure drop through the valve falls below the cracking pressure, the valve will close.
  15. Robster1us

    Applicability of the M.W. Kellogg Methods

    After reading some opinions in some of the threads in this forum, I would like to get some specifics, if possilbe, on the applicability of the M.W. Kellogg methods. Just in case anyone didn't know, brand new paperback copies of the second addition are available for around $35 on Amazon. As...
  16. Robster1us

    Pipe Stress Analysis and Existing Systems

    Amarmona, If you have a new question, please start a new thread. Thanks
  17. Robster1us

    Pipe Stress Analysis and Existing Systems

    Hi MJ. Thanks for your input. I've written many pipe specs and purchase requirements for piping systems, both for B31.3 normal fluid service and B31.5 systems. That's not really what I'm after. Knowing that a pipe provides the proper strength, and properly specifying it per the code (with...
  18. Robster1us

    Pipe Stress Analysis and Existing Systems

    Thanks Pipes. You did get to the heart of my question. I wasn't trying to jump around on topics so much as give background to why I'm asking. I've learned in this forum that many people will read something that seems like areasonable question and put no thought about what the person is really...
  19. Robster1us

    Pipe Stress Analysis and Existing Systems

    OK, maybe I need to rephrase. I am talking about just the stress analysis portion of determining minimum wall thickness, which can be done during new system design to give some guidance to the PSM contractor years down the road on interpreting results. API 579 would not, I believe, tell you...
  20. Robster1us

    Pipe Stress Analysis and Existing Systems

    I would like to thank everyone who responded to my previous thread on B31.3 Pipe Stress Analysis. It was quite informative. I have received and been reading both the MW Kellogg and Peng and Peng books that this community suggested. They both contain a hug amount of information that will take...

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