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  • Users: Ehzin
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  1. Ehzin

    ASME / Double design temperature for a welded line

    Fran67, Is the orientation of the deadleg vertical or horizontal? And you mention the dead leg length is 5m what's the size and length of both the run and branch line? For liquid cryogenic lines, a concept is employed on extended bonnet valves where the packing is orientated above the line and...
  2. Ehzin

    Pressure testing of spiral heat exchanger for gasket leak

    Tundra, As an additional note, at least for the spiral exchanger construction I'm familiar with, you can actually perform a hydro of one side with the cover off on the other. It requires very important consideration to prevent the spiral from extruding out but it can be done. There are many...
  3. Ehzin

    Welding Deformations - Split T

    I need to look at the above discussion in more detail but is it feasible to fabricate your split enclosure just by splitting the relevant pipe size versus rolling plate? Thanks, Ehzin
  4. Ehzin

    psv for a LH2

    Latexman, You mention running fire calculations for the entire vessel surface area. If the only fuel for a fire is the tank contents itself shouldn't that require a review of the possibility of a sustained pool fire? You may be referring to another fuell source but I just wanted to clarify the...
  5. Ehzin

    Temperature correction factor

    You need to elaborate. Are you referring to temperature correction factor to determine appropriate hydrotest pressure? Confirm the vessel is designed to ASME Section VIII, Div. 1 or if it's another code. From there you can receive further direction. Thanks, Ehzin
  6. Ehzin

    Pressure testing of spiral heat exchanger for gasket leak

    Tundra, Look into the construction of your particular spiral exchanger. Typically, the gasket seal on each side of the exchange only seals one of the two streams from external leakage; i.e. hot and cold side each have a seal. Testing only one side wouldn't expose the other side gasket to...
  7. Ehzin

    ASME B16.38 Compliant Ball Valves

    What code is the system designed to? As an example B31.3 doesn't include B16.38 valves in its "Component Standards" but other codes might. This isn't a comment on whether or not it can be used per that code. Clarify what the system is designed to and that might explain if a B16.34 valve is a...
  8. Ehzin

    Spiral wound Gaskets material - SS316 instead of SS304

    While I don't disagree with attempting to inform the client of the possible benefits in performance and availability of an "upgrade" material this shouldn't allow a vendor/EPC/etc... to make that decision to upgrade for them. I hope this doesn't come off as an assumption of your particular...
  9. Ehzin

    Liquid Drain Valve

    A drawing is needed. You want to drain liquid but seem to indicate that a low point bleed is not plausible. How do you intend to defy gravity? Thanks, Ehzin
  10. Ehzin

    Root Valve

    As mentioned, root valve has very little technical meaning. A "Root" valve is the first valve off a process line that provides the first isolation. It provides the branch connections to hook up other instrument/etc... It simply is the first valve to provide isolation from a live system...
  11. Ehzin

    Emergency Vent

    Regarding a trip at the pump, wouldn't this indicate that the pump is no longer pumping in and therefore remove having to worry about this scenario. In regards to the pump in rate versus relief size, I'm assuming this is based on some general logic about flow restriction. If I'm pumping into a...
  12. Ehzin

    Tube rupture case

    So this is just for information as I don't see this applying but if the design temperature of the tube side is somehow lower than the shell, then during a tube rupture you could exceed the tube side stress limit before the relief device on the shell side lifts properly. I understand this very...
  13. Ehzin

    Thermal Expansion Coefficient (e); B31.3 Appendix C

    Another good resource would be ASME Section II, Part D, assuming you have it available to you. Instead of just mean or total expansion from 70°F to an indicated temperature it has instantaneous thermal expansion at a given temperature. If you wanted to find the growth from 300°F to 800°F you...
  14. Ehzin

    Is a PSV required if there are no credible scenarios?

    If you've determined that a fire, while unlikely, is possible then I don't think UG-140 would be appropriate. Regardless, you mention that local standards require a relief device so that's fairly straightforward, unsure if this is legal jurisdiction or company standards. In regards to meeting...
  15. Ehzin

    Why vent-line ice-covered at nitrogen tank depressurization?

    Ghensky, You mention speculation regarding the tank being double jacketed. If this is a facility in which you work that has control over this equipment can this not be confirmed? And what is the actual internal temperature of the equipment. Georgeverghese mentions very little temperature drop...
  16. Ehzin

    Texas: Code and Non-code vessels

    To start off, I believe Louisiana is the other state you mention although I expected there to be more than just two. With a proper shop and a properly designed and fabricated vessel the difference really comes down to paperwork. You can purchase a vessel with the same material, welding, and QC...
  17. Ehzin

    Low Differential Pressure -Conventional Safety Valve

    To expand on your second section (Too much afterthought) regarding the 32.5 psi for your differential. Assume for a moment your downstream system reached 50 psig and then your hexane relief valve stopped because pressure temporarily declined. If you continue to increase the pressure on your...
  18. Ehzin

    Low Differential Pressure -Conventional Safety Valve

    I believe to expand on George's comment (Apologies if this isn't the preferred format), you reach a steady state where the relief valve has 75 psig + 1.1 times overpressure of 82.5 psig to limit overpressure of the vessel. The device, assuming it's a conventional spring loaded relief valve...
  19. Ehzin

    Why vent-line ice-covered at nitrogen tank depressurization?

    It's possible it's a jacketed vessel with liquid N2. Without more info this is just speculation. Thanks, Ehzin
  20. Ehzin

    Why vent-line ice-covered at nitrogen tank depressurization?

    Well, my background is mechanical so I'm a bit rusty but trying to control the rate to prevent icing could be a challenge. The easy way is to throttle the valve in the field and see if there's an acceptable throttled valve position where icing doesn't occur. One of the two following outcomes...

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