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  1. belowzero

    cryogenic valve seat craking

    jabonet states that the temperatures goes up and down above -196 Deg. Therefore its probably quite critical and thats why soft seats have been chosen.
  2. belowzero

    cryogenic valve seat craking

    Metal seats do not tend to be bubble tight, as I would assume thats why soft seats are being used. That said triple offset valves are a 'metal seated' but comply with soft seat leak rates. Soft seats do not like uneven temperatures, if the valve is cold and one side warms up the disparity in...
  3. belowzero

    LNG plant, valve selection and orientation

    To answer your questions though: 1. Yes depending on what standard you want to comply with. 2. Installation should be no more than 45 deg from vertical. 3. Yes, these valves will typically get to lower temperatures. 4. As Q2 Stem position and length apply to any type of valve, ball, gate TOSV...
  4. belowzero

    LNG plant, valve selection and orientation

    Take a look at FAQ 774-566 its for Cryogenic valves but also relates to low temp valves such as you require. The shaft can be as much as 45 degrees from vertical if the extension is long enough, try and comply with a known standard such as shell's then you cannot go wrong, these have been put...
  5. belowzero

    cryogenic valve seat craking

    In response to jabonet's original question, can I suggest a basic increase in good thick insulation to stop the valve reaching higher temperatures and as the valve gets down to -196 the material will be kept colder and may even stay chilled for the next days operation, if it does you will then...
  6. belowzero

    Ball Valves

    It sounds as though you may be talking about a Double block and bleed valve, the 'o'ring allows the seat to move with the ball slighlty yet still seal against the body of the valve stopping any flow across the back of the seat. Pressures are lower than normal use because of the 'o' ring...
  7. belowzero

    How would you call such a valve?

    unclesyd is mostly right, the other point is that the vee port was either a metal seat with the formed aperture and the use of a standard ball, or a solid ball machined with a parallel cutter forming the 'Vee', the Vee that is talked about here and the ones we made have a tapered Vee, this...
  8. belowzero

    How would you call such a valve?

    We made a very similar item many years ago in NJ from a solid ball. However it was not actually given a name as it was the customer themselves who provided the sketch. The stops were changed to allow the ball to rotate 180 degrees. As far as we were concerned it was a very crude manual control...
  9. belowzero

    Hydrotesting with glycol

    roadbikeruler (Petroleum) says so I pressume he does mean 100% Glycol. Surely this is quite a difficult test, much like Helium against Nitrogen when doing gas tests, as the Glycol has a very small molecule and is known to be very 'searching'. This would surely find leaks that would not...
  10. belowzero

    Watertightness - spray testing: The physics of leaks

    Jspisich - You don't need a 'vent' to eliminate pressure/vacuum if you use a diaphragm, therby maintaining the 'atmosphere' within the unit. Obviouisly designed large enough to cope with temperature changes involved. B
  11. belowzero

    Inconel 625 Low temp service

    Sorry this is rather fractured. I have always found great difficulty getting negative temperature properties for metals unless they have been specifically designed for that purpose i.e. 17.4 ph 1150MM. In the years I have been in Cryogenics we have always had to approach the manufacturer for...
  12. belowzero

    Inconel 625 Low temp service

    Have a look at http://www.upmet.com/media/625.pdf B
  13. belowzero

    Inconel 625 Low temp service

    UNS N04400 will do -196 Deg C. B
  14. belowzero

    High dp across ball valve

    zdas04 (Mechanical)- Don't mislead the guy by stating that all 'Trunnion' ball valves have springs as you did in thread408-134074. Take a 'Jamesbury' 10" 6000 series, these purely use polmer seating technology and a very unique design to load the seat onto the ball despite being trunnion ball...
  15. belowzero

    Fire Safe SDV

    Take a look at FAQ 408-589, I wrote the FAQ quite some time ago but it still gives a good representation of the facts. These are general fire testing standards for 'any' application where the valve must isolate a potentially volatile media. Most 'certified fire tested' valves can be used for...
  16. belowzero

    Control ratio

    bcd, Hmmm Unseating and breakout of metal or soft is another word for 'jump' sorry if the terminology was a little simplified. Globe valves don't have the same sealing characteristics as butterfly and ball. Metal seated valves are more tolerant to working near the closed position as they...
  17. belowzero

    PTFE Packing for Fugitive Emission control

    ISO 15848 certification is one thing but as the reason for FE is to exclude noxious and harmfull chemicals the use of Graphite has to be questioned where medias exist that readily leach and errode graphite. Phosphoric acid comes to mind as an example. PTFE packing is the only suitable material...
  18. belowzero

    Control ratio

    The 'Jump' being discussed in the soft seated valve is the characteristic of the material rather than design, PTFE based seats are prone to 'cold flow' i.e. the small movement of the material at high load points, so at the lip or sealing point of a valve there is typically a higher load which...
  19. belowzero

    Valve seats for 1500# and 2500# ball valve

    I gather you require bubble tight shut off and hence the soft seats? These are extremely high rating for 'soft seated' valves. You should only use a known company who have a large amount of history and can show you the quantities and industries these valves have been placed in. Unfortunately I...
  20. belowzero

    Incorrect Nickel Plating Thickness

    Most of my silver plating experience is with a base of Beryllium copper on connector pins and other electrical components, Plus lots of other types of plating. If the plating has a uniform thickness throughout and this is higher than you require then obviously the components need less time...

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