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  1. packdad

    Valve design question re: Pressure on bonnet

    Let's say you have a valve with a bonnet that bolts to the body. It's a gasketed connection with the gasket located within the bolt circle. When the pressure force on the bonnet is considered during valve design, do you assume design pressure only within the diameter of the gasket, or do you...
  2. packdad

    Hot Tapping in Compressed Air Line

    Additional notes: When we attached the sockolet to the 8" mock-up pipe prior to the 3/4" hot tap, the 8" pipe was dry and this resulted in some deformation of the 8" pipe around the sockolet. It may also have locally hardened the 8" stainless steel pipe, which may have slowed the drilling...
  3. packdad

    Hot Tapping in Compressed Air Line

    If this evolution is a big concern, you might consider a mock-up. I had a vendor perform a mock-up of a hot-tap years ago in our maintenance shop because we were concerned about foreign material entering our system. We wanted to add a 3/4" sockolet connection to a 8" Sch.40 water-filled...
  4. packdad

    please help...please

    Well, if you know the mass flow rate, specific heat, and temperature difference of the dough, then the overall heat transfer rate is simply: mass flow rate * specific heat * (T_out - T_in) Right? But if the dough is very thick and has a low thermal diffusivity, then perhaps the measured...
  5. packdad

    TDH calc question

    I'm not very familiar with rotary pumps, but wouldn't the TDH be the same regardless of direction of rotation, as long as the speed is the same in both directions? It seems like it would, but like I said - I'm just assuming. I guess you don't have suction and discharge pressure gauges...
  6. packdad

    Is "heavy gauge" defined?

    Is there a definition for "heavy gauge" sheet steel? In other words, does a sheet need to be greater than some minimum thickness to be called heavy gauge? Or, as I now suspect, is this more of a subjective term?
  7. packdad

    Requirements for an N-Stamp?

    I guess I posted in haste. NA-3310 specifically states that an N certificate holder is responsible for the design.
  8. packdad

    Requirements for an N-Stamp?

    In order to have a Section III component N-stamped, does it require that both the design and fabrication be done by an N certificate holder (as opposed to just the fabrication)? That's been my understanding, but I've forgotten the basis. I'm off to go flip through the Code, but I thought I'd...
  9. packdad

    Relocating a chilled water expansion tank

    In this case, the friction head loss between the new tank tie-in point and the pump suction will be more than compensated for by the static head of the tank, so we are OK on pump NPSHa. Calculated dynamic losses between the new tank and the pump are around 22 FT whereas the elevation difference...
  10. packdad

    Relocating a chilled water expansion tank

    We have a chilled water system with a closed, pressurized expansion tank located near the mid-elevation of the system. We want to relocate the tank above the topmost elevation of the system so that it may be vented to atmosphere and not require air overpressure. The current tank ties into the...
  11. packdad

    Cross-Ref. Between Numbering Systems and Grades?

    Thanks for the reference. And you're right, Steve: My older hard copy references do not have UNS information, but if I pull up an ASTM standard using our on-line reference service - there's the UNS info!
  12. packdad

    Cross-Ref. Between Numbering Systems and Grades?

    Just curious if there exists some form of a cross-reference between the ASTM standard designations (eg, A693) and the UNS designations (eg, S174000)? Also, is there a cross-reference between the ASTM numbers and the various types of stainless steels (for example, a listing of all the ASTM...
  13. packdad

    National Board registration req'ts in N.C.

    Thanks for the feedback. Right now, we're standing by the requirements of our spec. I'd be VERY surprised if the vendor made a fuss about this. And I agree with you that we should not be of the mindset that we'll always try to accomodate a vendor anytime they want to take exception to a...
  14. packdad

    National Board registration req'ts in N.C.

    I work at a nuclear plant in North Carolina. I am ordering some ASME Section III Class 3 check valves for a system that sprays cold water into the containment building under emergency conditions. The question has come up: Do these valves have to be registered with the National Board? I am...
  15. packdad

    HEAD OR PRESSURE

    I found this thread while searching for an answer as to whether a pump TDH curve must be adjusted for changes in specific gravity (SG). For example, if a vendor develops a TDH curve for (pressurized) water at 350 deg F, what adjustments must be made, if any, to know what curve to use for...
  16. packdad

    Cv conversion to other units

    As noted in Crane Technical Manual 410, "The Cv coefficient of a valve is defined as the flow of water at 60F, in gallons per minute, at a pressure drop of one pound per square inch across the valve." From that description, I'd think you could convert to any units you like (eg, liters per hour...
  17. packdad

    Insert Valve in Full Pipe

    As has been stated, if there's room, a freeze seal is probably your best option, although piping from the seal back to the tank would have to remain in place (obviously). There are companies that specialize in installing freeze seals, and they can mobilize very quickly. I know Team Industrial...
  18. packdad

    Sulfur vs Peroxide-Cured EPDM

    I've now heard from several people that peroxide curing will give the same or better performance than sulfur curing, and that they're both about the same price, so I guess I'll stick with my request for peroxide-cured EPDM. That's a good point about seal lifespan. I also think that a harder...
  19. packdad

    Sulfur vs Peroxide-Cured EPDM

    I'm supposed to order new EPDM seats for some butterfly valves that are used for isolation in an HVAC system, and I'm told that peroxide-curing is preferrable to sulfur-curing. Why? It should be noted that we would like to minimize compression set in this application, and from what little...
  20. packdad

    Aluminum beer bottles

    Or maybe a polymer lining? I know steel cans are routinely lined, but I'm not sure about aluminum.

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