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  1. don1980

    Short-term Storage of methanol in plastic container

    Jack, your only constrained by the plant owner's tolerance for risks. There are no reg's that apply in this case.
  2. don1980

    Heat exchanger

    Leaks are happening because the gaskets are not compatible with the fluid, or because the unit isn't properly tightened.
  3. don1980

    Temperature Correction factor for ASME Section 1 Safety valve from Fukui Manufacturer.

    If you provided the manufacturer with the operating temperature (370C) on you spec sheet (and I assume you did), then the manufacturer would have provided the CDTP. The CDTP is generally stamped on the nameplate. If you don't have a CDPT then contact Fukui for that value.
  4. don1980

    Delta T for Steam on Heat Exchanger

    Some subcooling of the condensed steam may occur, but for design purposes that should/can be ignored. The design intent is to use the heat that comes from condensing the steam. Thus, for design purposes the steam side and condensate are in thermal equilibrium (same temperature). The temperature...
  5. don1980

    Firecase for LNG doublewall tank

    Refer to a text that explains heat transfer through a composite wall. With a double wall you have multiple layers of thermal resistance. Do that to calculate the heat transfer rate to the fluid in contact with the inner wall. The heat input rate to the LPG will obviously be much less than that...
  6. don1980

    Sizing of an additional PSV on a brownfield system

    Morten, I agree that the only practical option is to lower the set pressure of the first PRD. My point was that PED actively states that one can set the second device at 105% MAWP. So it's not against regulations to do that, but by saying this, the PED authors apparently didn't recognize the...
  7. don1980

    Sizing of an additional PSV on a brownfield system

    Adding to Morten's comments, this PED restriction (limiting the relieving pressure to 110% of MAWP even when multiple PSVs are used) effectively undermines the benefit of setting the second PSV at 105% MAWP. That's because the second valve isn't fully open - there's not enough overpressure for...
  8. don1980

    Atmospheric Tank Nozzle Sizing

    The real constraint is the vent line's pressure drop and not its velocity. Sizing an atm vent pipe is simply a line sizing exercise in which the pressure drop is limited to the max allowable pressure in the protected vessel. For example, if the max allowable tank pressure is 1 kPa, then the vent...
  9. don1980

    Fully charged vessels with LPG and risks

    As inferred by LittleInch, to be objectively safe you'll need to remove all the hazardous materials, and close the plant. That is, find another way to make money. But, you'll then find that other hazards exist in almost every industry. The point here is that we're in the business of managing...
  10. don1980

    Which rated flow for DP calcs

    Since this is for a European facility, I would think that you're using an EU harmonized standard (e.g. ISO 4126) for the relief design. Compliance with PED is easier when using harmonized standards. However, one can also use a non-harmonized standard such as ASME Sec VIII - it just requires a...
  11. don1980

    Latent Heat of Vaporization and Molecular Mass of Vapor for Asphalt/Bitumen and Used Motor Oil

    When exposed to fire, the liquid in the tank doesn't provide any significant cooling protection for the shell unless/until that liquid starts to boil. Once boiling starts (which occurs at the inner wetted surfaces of the shell, the Hvap helps limit the temperature of the shell metal (Hvap...
  12. don1980

    Latent Heat of Vaporization and Molecular Mass of Vapor for Asphalt/Bitumen and Used Motor Oil

    Since you're asking about the Hvap of this material, I assume you're performing calculations for a fire exposure case. Before proceeding with that design, consider the temperature at which this asphalt/bitumen boils and consider the likelihood of the tank will remaining intact, since the wall...
  13. don1980

    Rupture disc at PD pump discharge

    RD's will reliably burst when they need to burst - and they'll reliably burst when they're not needed. That's especially true in a liquid-full system, and it's exponentially true for applications like the discharge of a pulsating pump. That's an exceptionally bad application for an RD. For...
  14. don1980

    twin heat exchangers

    Gas-side heat transfer (film coefficient) is highly sensitive to turbulence (Nre). Since you're obviously getting better heat transfer in E-A, one possible explanation is that the NG side of E-A has more pressure drop (resulting in higher Nre, and better HTC) due to the friction loss in the NG...
  15. don1980

    Perforated Pipe Distributor Design for diffusion of gas in a aqueous solution

    If distributor performance is critically important, then you'll have to do some experimental testing. Calculations can't reliably produce in a design that meets performance requirements.
  16. don1980

    Fire water alternate utilization

    There's nothing sacrosanct about F/W. The relevant question is whether this use of F/W impairs the ability of that system if a fire occurs. If the answer is no, then I see no problem with this.
  17. don1980

    Liquid Thermal Expansion For Systems under Shed

    In the real world, the question of whether liquid thermal expansion protection is needed is a very easy one to answer. Just ask yourself whether the liquid-full system can be isolated, and whether the fluid temperature can rise while it's isolated. If both of those answers is yes, then the...
  18. don1980

    Injecting 93% sulfuric acid into a water tank

    I agree with Ed about not injecting this acid directly into the CS vessel. I wouldn't inject directly into the tank even if the tank had a mixer. As a young engineer I did something kind of similar to this. It turned out a costly mistake for my employer but a valuable personal learning lesson...
  19. don1980

    Engineering Drawings

    I haven't looked but I'm confident you can find lots of explanation/guidance on the internet. A new process design starts with index flow diagrams, and then progresses to P&IDs which show the details. P&IDs communicate the scope of the process design to the detailed engineers. Basically...
  20. don1980

    Tube Side Velocity Limit for Shell and Tube Heat Exchangers

    Pavan, I assume you're using a heat exchanger software program such as HTRI, or similar. Use that to gain a good mental picture/understanding of the various sensitivities and trade-offs. Recognize that trade-off are an inherent part of exchanger design, Start by identifying the core design...

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