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Recent content by jt1234

  1. jt1234

    Div. 1, UG-37, Correction factor "F" not making sense

    Trestala,, 0 degree is the longitudinal axis, you will see circumferential stress at the cut plane, which is hop stress and is PR/t. F =1, I have no question as it is the maximum stress plane, need the most reinforcement area. You are making the stress direction wrong. At 90 degree, the cut...
  2. jt1234

    Pressure vessel under negative Pressure

    If you have negative pressure on the top, that means somewhere in the top or the pipe line got plugged or stuck while you are draining the water out from the lower section. Check the piping system connecting to the top head to see where is the bottleneck or any valve unnecessarily closed during...
  3. jt1234

    Div. 1, UG-37, Correction factor "F" not making sense

    Dear experts who specialize in nozzle reinforcement: Div. 1 UG-37, Correction factor “F” and Figure UG-37, if code insists it must be 1.0 for re-pad at theta =90 degree, which is the circumferential plane with the longitudinal stress of PR/2t , then “F” shall be 2.0 for re-pad at theta =0, which...
  4. jt1234

    Effect of external corrosion allowance on UG-40 normal to shell limit calculation

    Treat all nomenclatures as the final corroded thickness. That's all, so simple, no magic.
  5. jt1234

    External Pressure Stiffner Ring

    Disagreed, It is just personal preference either by personal preferred "distance", or written in specific company's vessel spec talking about how far away, 2", 3", 2t, 3t, etc., no universal guideline. There is no prohibit to not welding attachment on top of weld. Period.
  6. jt1234

    External Pressure Stiffner Ring

    Yes it is acceptable. There is no restriction any attachment can not be welded on top of weld. It is just personal preference not to do that as afraid of not able to NDE the butt weld or higher stress riser in the welding zone. But nothing wrong.
  7. jt1234

    Vessel for Hydrotest over MAWP

    "Test pressures should be a once in a lifetime event otherwise they become the MAWP.": Not correct and not making sense.
  8. jt1234

    Vessel for Hydrotest over MAWP

    Your focal point is the hydrotesting, not the MAWP. That means you shall ask customer what is the hydrotest pressure for the vessel. If it is below 5372 psi, you shall not use that vessel to do hydrotest unless you want to redesign your heater to lower the test pressure to match vessel's. If...
  9. jt1234

    PAUT TEST

    In addition, our welding engineer advises as follows:
  10. jt1234

    PAUT TEST

    Yes you can. PAUT is good for heavy wall in lieu of X-ray.
  11. jt1234

    nozzle-head PWHT

    Thickness is considered "normal" to the surface, not measured in the hill side length, so you don't need local PWHT. Correct me if I am wrong. We have so many hill-sided nozzles in all kinds of projects, never have any one need local PWHT. Also the so called "local PWHT" is to wrap entire shell...
  12. jt1234

    ASME VIII-1 Nozzle Spacing Clash

    Just ignore the warning from PV Elite. We dealt with close nozzle spacing almost in every project, with only 2"-3" gap between flanges. You can use thicker re-pad (not thicker than 1.5 x shell thickness and 2" minimum width, our own practice), or thicker nozzle, local thicker shell, integral...
  13. jt1234

    Reducing flange analysis using FEA or Div 1

    More clarifications to my post, to see if anyone can help: This vessel was just fabricated and passed hydrotested and installed already. However, looking back in vendor's hundreds of pages of calc found no calc for this reducing flange. The reducing flange has the thickness of 123.9 mm, the...
  14. jt1234

    Reducing flange analysis using FEA or Div 1

    Dear all, I have a Div. 1 vessel with top 36" nozzle, 600# B16.47 series A, connected to a forging flange with hub ( we call it reducing flange) and a 18" outlet pipe as shown. Can this reducing flange be classified as custom made component, not fitting UG-34, UG-39, Appendix 2 or Div 2 Part...
  15. jt1234

    Deaerator Inspection Frequency

    Lost million $ at every shut down. So you don't necessary shut down every year for inspection or repair if it can be continued operating as long as it does not impact pressure part. Also there are many monitoring devises in the equipment that can tell whether it shall be shut down for repair...
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