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  1. JoeWong88

    Thermal Oil Expansion Tank in Fire Case

    If hot oil can reach 400 degC, probably the tank steel already reach > 500 degC... You may check the vessel strength at this temperature and see if the vessel collapse before it reach this temperature. Check and tell us... There will be vapor space in the tank. Check if the liquid expansion can...
  2. JoeWong88

    Design conditions for pipe before PSV

    You have not uploaded the sketch, it is difficult to visualize. If the block valve is located downstream of pressure control valve but safety relief valve is between the pressure control valve and block valve, then the spec break can be located just Pressure control valve exit flange. If the...
  3. JoeWong88

    Butane Storage Bullet PSV or RD

    duncan8943, No doubt you can install a small PRV for small relieving scenario and a large relief device for large relieving load. This is pretty common in many installation. Neither PRV nor RD will definitely protect a vessel from fire. Vessel will eventually collapse due to fire...
  4. JoeWong88

    relief valve set pressure Q

    Cutie, If the question is non related to original post, it is always better to open a post. PRV and Rupture disc will have different manufacturer tolerance. RD may be about 10% (confirm with manufacturer) and PRV probably much lower. RD may need to set lower pressure. But under positive...
  5. JoeWong88

    check valve on Rupture disk outlet

    Downstream of pressure relief device, devices potentially causing partial or total blockage which further limit the relief flow shall be avoided. Check valve is one of the potential device. Burst disk indicator (proposed by Latexman) and buckling pin system with positional switch (proposed by...
  6. JoeWong88

    relief valve set pressure Q

    EngCutie, When deciding on the PRV set pressure, at least two points you may have to look at. Benthayer, JAC, Latexman, etc has given you the first point where set pressure can same as or lower than MAWP. Second point you have to look at is premature opening of PRV by considering - maximum...
  7. JoeWong88

    relief valve set pressure Q

    EngCutie, When deciding on the PRV set pressure, at least two points you may have to look at. Benthayer, JAC, Latexman, etc has given you the first point where set pressure can same as or lower than MAWP. Second point you have to looks at is premature opening of PRV by considering - maximum...
  8. JoeWong88

    How to know if a PSV has opened?

    Spring loaded type PRV is understood as "slow-acting" pressure relief device compare to bursting disc or buckling pin. It may not lift when it see only pressure spike especially in low compressibility liquid system. For instance, HP gas in tube side and cooling water in shell for a Shell-&-Tube...
  9. JoeWong88

    Constant and Variable Backpressure

    Sheiko, I don't disagree with what you have done, however sometime proper communication is crucial. Set pressure Some could interpret set pressure as pressure when PSV start to open and other interpret it as Pressure for Net Spring Setting (as what we have discussed via personal...
  10. JoeWong88

    PSV Isenthalpic or Isentropic ?

    Flarenuf, Your observation is known... The thermodynamic path that an engineer would like to consider is subject to what he really wanted to look at and how conservative he would like to design for. If you intended to derive low temperature limit, certainly you can not ignore the isentropic...
  11. JoeWong88

    MAWP vs. Vapor Pressure?

    I hope the vapor pressure of your product is referring to ambient temperature (min to max.) If so, then operating operating (min - max) will be the vapor pressure. I hope the following will help you Definition of Terms Related to PRESSURE JoeWong Chemical & Process Technology
  12. JoeWong88

    API 520 or API 2000?

    API STD 521 and API STD 2000 are non-exclusive between each and other. Certain discussion in API Std 521 may still applicable to a common storage tank... skearse (Chemical) has given you some good guideline. What is the maximum allowable working pressure (MAWP) of "Thin film evaporators" ...
  13. JoeWong88

    Liquid full vessel - relieving temp?

    This subject to fluid characteristic i.e. foamy, reactive and construction of the equipment i.e. narrow-flow passage like jacket vessel. You may be interested in "How Fluid Characteristic affect 2 phase Relief via PSV on Liquid filled Vessel Exposing to External Fire" JoeWong Chemical &...
  14. JoeWong88

    Backpressure correction for balanced bellows

    PRV A with lower set pressure will have lower spring force. When PRV A lifted, with same relieving pressure, it tends to open slightly more to allow larger flow. The PRV B may not be undersized if it can take half the relieving flow. JoeWong Chemical & Process Technology
  15. JoeWong88

    Multistage RO

    Beside cavitation, it is also used to avoid acoustically fatigue failure of pipe. JoeWong Chemical & Process Technology
  16. JoeWong88

    Vapor breakthrough relief

    prq123, Every project or company has their own believe, risk or tolerance, etc. However, it shall be written down as standard, basis and policies to be complied to. If these documents do not believe in Safety Instrumented System (SIS) can safeguard the system (where API allow now), and do not...
  17. JoeWong88

    Using oversized PSV

    MechBRR, One of the problem link to oversized PSV is chattering. Chatterng could lead to seat damage, leakage, etc. PSV normally can take load from 25-100% of it design load (subject to PSV type - only manufacturer (not vendor) can advise). So again, without knowing the relief load (especially...
  18. JoeWong88

    Vapor breakthrough relief

    prq123, I am aware of all the API statements as mentioned by you. What you have said is correct. This is gas blowby or gas breakthrough case. The only point i would like to add to your statement is the upstream pressure may be upto maximum pressure before it trip i.e. PAHH as control system...
  19. JoeWong88

    Using oversized PSV

    MechBRR, Fire case for vessel, there is liquid filled, 2/3-phase in vessel or gas filled vessel. Similarly, there is liquid filled gas filled for HX (if cooler or heater) but 2-phase in HX (if condenser or evaporator). Comparing surface area of vessel and HX can not justify same PSV to be used...
  20. JoeWong88

    Vapor breakthrough relief

    prq123, What is the cause of FV-1 failure ? Is this cause can result failure of FV-1 and LV-1 failed simultaneously or sequentially ? If not, can this be considered double jeopardy ? You consider : - FV-1 failed to close - LV-1 stay at position (mean the controller failed to control) - Low-low...

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