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Recent content by TGS4

  1. TGS4

    Question about Ratcheting (ASME Sec. VIII Div.2)

    You’re mixing failure modes now. Don’t do that. Plastic collapse and ratcheting are completely different. The fatigue curves have the built-in assumption that you don’t ratchet. Not really. And if you take hundreds of cycles to demonstrate that you don’t ratchet, can you really say that you...
  2. TGS4

    Question about Ratcheting (ASME Sec. VIII Div.2)

    You’re mixing the elastic analysis method with the elastic-plastic methodology. The two are not interchangeable. Focus on one or the other only.
  3. TGS4

    General Flange Design.

    Draw yourself a free body diagram. Properly consider the end conditions. You’ll see horse what SnTMan says is correct.
  4. TGS4

    MAWP certification

    I think that you have identified your fundamental problem. If this manifold is intended to be installed into (for example) an ASME B31.3 pressure piping system, then it would need to be designed in accordance with ASME B31.3, or one of the standards referenced within B31.3. Similarly if you...
  5. TGS4

    Section modulus ratios

    Where are you getting this from? Is there a reference to this "understanding"?
  6. TGS4

    Understand local vs gross structural discontinuities

    Please review paragraph 5.2.1.2 in ASME Section VIII, Division 2, Part 5.
  7. TGS4

    Shakedown strain hardening question

    Incorrect. This effect is independent of strain hardening - it is premised on an assumption that the material behaves elastic-perfectly-plastic. Please review the explanation provided in the "Criteria Document" from 1972 - also provided in ASME PTB-1 (2104).
  8. TGS4

    Shakedown question

    What is a "negative margins for primary stress"?
  9. TGS4

    MAWP certification

    What design code is this designed to?
  10. TGS4

    Can Service Pressure Exceed Design Pressure?

    Your colleague will need to read the Code themselves. Might find a thing or two interesting while in there.
  11. TGS4

    Can Service Pressure Exceed Design Pressure?

    As noted by GD2, these limits are specific to Section III Construction. Such service levels do not exist in Section VIII construction (at least in Division 1 and 2). So, for Section VIII, Division 1 and 2, the internal pressure is not permitted to exceed the Design Pressure / MAWP.
  12. TGS4

    Trying to understanding primary plus secondary stress difference range and why we evaluate it.

    I'm going to assist you a little to clean up your terminology to match the current version of ASME Section VIII, Division 2, Part 5 - will help with your understanding a little. The allowable (equivalent - or von Mises, if you will) stress is S, not Sm. The primary stress is divided into two...
  13. TGS4

    Risk of through hole on live piping

    The appropriate approach is to perform a fitness-for-service assessment (typically in accordance with API 579-1/ASME FFS-1). If the pipe is not deemed fit-for-service, then the options are rerate, repair, or retire. Other than a clamp repair (which you have stated cannot be installed), what...
  14. TGS4

    Local Vs global stress and fatigue analysis in fea analysis

    ANSYS doesn’t help you with general vs. local stresses. And your suggestion for using M+B only (and not peak) for fatigue doesn’t follow the Code. Unless they have a Code reference that says otherwise, my recommendation is to ignore @TomLee777 ‘s advice.
  15. TGS4

    some questions regarding the buckling analysis(5.4 of ASME VIII-2)

    1. That is the through-thickness stress - entirely predicted from thin-shell theory: the negative of internal pressure on the inside and zero on the outside. This will not lead to buckling. The focus is on hoop and meridional directional stresses. For example, in a torispherical head, under...
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