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Recent content by CHD01

  1. CHD01

    Bird Screen on PSV outlet Required?

    Why are you concerned about the minimal probability of a bird sitting atop a discharge line. If they are there they will not be there long. The more you learn, the less you are certain of.
  2. CHD01

    Fire case - Latent heat for multicomponent system

    Joe is correct that first you must understand the mixture and whether seperation will occur for lower boiling components for example. The more you learn, the less you are certain of.
  3. CHD01

    Fire case - Latent heat for multicomponent system

    The latent heat of a mixture is equal to the sum of each component latent heat multiplied by its mass fraction. The more you learn, the less you are certain of.
  4. CHD01

    Cold flare maximum tip diameter limits

    I know of no limits regarding a maximum vent or flare tip diameter published in API520 or API521 other than avoiding too low a velocity for dispersion which you have alredy covered in your analysis. The more you learn, the less you are certain of.
  5. CHD01

    Acceptable to Size PSV on U/S Orifice Size?

    Those advising you are correct. Downstream orifice pressure for calculating the required relief flow should be based on the downstream relief valve set pressure plus 10%. Dp across upstream valve orifce may be based on either downstream or up-stream density if less than 10% dp across the valve...
  6. CHD01

    Acceptable to Size PSV on U/S Orifice Size?

    Those advising you are correct. Downstream orifice pressure for calculating the required relief flow should be based on the downstream relief valve set pressure plus 10%. Dp across upstream valve orifce may be based on either downstream or up-stream density if less than 10% dp across the valve...
  7. CHD01

    Anhydrous Ammonia Bottles; Are PRV's Required?

    My recollection is that K61.1 applies for API tanks below 15 psig; I don't believe it also applies for pressure vessels. Anyone have K61.1 available for review? High pressure cylinders and DOT applicable vessels require a relief valve. I support you previous responders. The more you learn...
  8. CHD01

    HIPPS vs PSV

    Sorry, but I sent that message before I was ready. You could perhaps use two 3-way valves using AG full bore ball valves. The upstream valve would have one inlet port with two outlet ports and the downstream 3-way valve would have two inlet ports and one outlet port. Between one of the...
  9. CHD01

    HIPPS vs PSV

    I was thinking of a manual 3-way valve (AG full bore ball valve) with mechanical link and/or key-lock system to guarantee positions. This is code allowed. This consists of one valve with one inlet port and two outlet ports with only one outlet port open at a time. If you take control valves...
  10. CHD01

    HIPPS vs PSV

    Pilot valves have a lot more relief capacity than a conventional valve with the same inlet flange connection - you might want to investigate whether that would help; plus you get around inlet pressure drop that way also. If the nature of the release is manageable a rupture disc by itself may...
  11. CHD01

    HIPPS vs PSV

    Understand. Some of the control valves have failed open rates that are absurd - basing flow sometimes on the internals being gone. Could you do something as simple as installing a restrictive orifice for the control valve? I have often done this; of course then the orifice becomes subject to...
  12. CHD01

    HIPPS vs PSV

    See the following article and Table 2B at the following website. The author gives his own SIL recommendation and the table 2B gives failure data on sping and pilot valves. I did not notice any data on rupture discs - but I did scan it rather quickly. I intend to read it more carfully later...
  13. CHD01

    Scaling relief loads by orifice size?

    While scaling (ratioing) the areas works much of the time to get a valves maximum flow, remember that you really want the relief device capcacity. Scaling will not always give you that. This is because the relief valve is always certified (rated) at 10% overpressure for section VIII valves (3%...
  14. CHD01

    Relief valve inlet/outlet lines

    To: dcasto Good point, yes I agree sometimes it is the destination of the discharge line that determines flange rating. Ultimately of course the engineer has to determine the max operating pressures for pipe sections and where the pipe code breaks need to occur. One other point on a discharge...
  15. CHD01

    Scaling relief loads by orifice size?

    FIrst , you need to review in detail the ASME CODE Section VIII Division 1, part UG for relief valves. You also need to review API520 and API 521 before you are ready to size relief valves. Now I will answer some of your questions which will only generate for you more questions as you realize...

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