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  1. xema77

    Seismic Tank Design

    Seismic for tanks and vessels are handled differently as tanks need to take into account the impulsive and convective seismic responses. For tanks have a look at API 650 Appendix E and EC. For vessels the best reference would be the applicable building code for your site location (ie. NBC...
  2. xema77

    ULC S601-07 Diesel Storage Tank

    It is an outdoor diesel storage tank and I was refering to an internal corrosion allowance. I had been led to believe that ULC S601-07 may have a corrosion allowance inherent in the design, however could not find anything to confirm this. Therefore I assumed, as FTank confirmed, that a CA...
  3. xema77

    ULC S601-07 Diesel Storage Tank

    I am purchasing a Diesel Storage Tank designed to ULC S601-07. This ULC specification provides the required thickness of the tank by tank size, no thickness calculations are required. A corrosion allowance was specified for the tank, however ULC does not seem to address corrosion allowance...
  4. xema77

    A SMALL MISTAKE IN COMPRESS.

    Do you have a liquid level above the girth flange? Sounds as though it is reducing for static head.
  5. xema77

    Tank Relocation - API 653

    I am investigating the requirements of relocating a tank. The tank is small enough that it will not have to be dismantled to be relocated. The tank service will change, however the tank was designed for a larger specific gravity and design pressure. Inspection of the tank has been carried...
  6. xema77

    C.A. for thickness of nozzle-API 650

    In previous editions of API 650 there used to be a note indciating that CA should be applied to the nominal nozzle thickness indicated in the table or the minimum calculated thickness. I do not know why this was removed, however I still use this criteria. Nozzle thickness shall be the larger of...
  7. xema77

    Tank Insulation

    We have used the system indicated by MATI22 above. It is more costly up front, but the installation was much quicker and it would be well suited for your situation. Attached is the brochure of the system we...
  8. xema77

    API 650 Design Wind Pressure

    There appears to be a discrepancy in the design wind pressure for API 650 tanks. -Section 5.2.1 defines the wind pressure on vertical surfaces to be 0.86(V/190)^2 or 18(V/120)^2 which is used in the wind overturning (Section 5.11) and Appendix F calculations. -When calculating the stiffener...
  9. xema77

    API-650 Table 5-21b

    I was confused with the units in table 5-21a Add 1. The pressure P and 0.08th in kPa mutliplied by diameter in meters result in units of kN. The wind and seismic moments are in N-m and W1, W2 and W3 are in kN and the resulting uplift loads are in N? Believe Ms & Mw should be in kN-m and the...
  10. xema77

    API 650 Uplift / Overturning and Tank Anchoring

    Thanks for the input
  11. xema77

    API 650 Uplift / Overturning and Tank Anchoring

    No, I don't think so. I was looking for a more constructive response. I believe that it is because 5.11.2 load case 1 uses 0.6Mw and appendix F does not factor the wind moment. It is difficult to tell with the factors that API applies to formulas in Appendix F. Ayone else have any input?
  12. xema77

    API 650 Uplift / Overturning and Tank Anchoring

    I am looking at the decision tree (Fig F-1) in Appendix F of API 650. The tank internal pressure is less than the weight of the shell & roof, however when I calculate Pmax it is less than the design pressure. F.4.2 indicates not to exceed Pmax. What needs to be done, I assume that anchoring...
  13. xema77

    Coating of Flange Faces

    I have an air receiver (DP = 1034 kpa) for which the bottom head and 1/3 of shell requires internal epoxy coating. Per the client specification, the nozzle neck, flange and first third of the flange face also require coating. The flange face coating detail indicates that a reduced coating...
  14. xema77

    Tank Venting

    Can someone please describe or provide references as to how to calculate the relieving capacity of open vents. I have calculated the required relieving rates using API 2000, however need to confirm if the gooseneck vents (open to atmosphere) have sufficient relieving capacity. Thanks.
  15. xema77

    Requirements for Foam System

    I have read through NFPA 11 which provides information to design a foam system for storage tanks (ie. number of nozzles, flow rates etc.). What is the criteria used to originally determine if a foam system is required or not. Are there guidelines based on the combustibility and volume of the...
  16. xema77

    SA387F11 casing

    This is correct, the preheat temp must be maintained until either the final PWHT, an Intermediate Stress Relieve (ISR) or Dehydrogenation Treatment (DHT) to among other things prevent cracking due to hydrogen entrapment. Working with Chrome-Moly Materials is quite specialized, I suggest reading...
  17. xema77

    Proper Interpretation of Shell Design

    Corrosion allownace need not be applied to the minimum thicknesses indicated in the table of 5.6.1.1. I believe that the minimum thicknesses provided are for fabrication reasons. Ensure you still consider all external loads such as wind, seismic and nozzle loads when considering plate thickness.
  18. xema77

    API 650 telltales - to plug or not to plug

    The telltale holes should not be plugged as this would not allow them to do their job of indicating a leak under the repad. A good practice is to pack the holes with greases to protect from the elements.
  19. xema77

    Attachments to Tanks

    Pressure Vessel Design Manual by Dennis Moss has a method of converting the equivalent areas of several strucural shapes into regular shapes that can be used with WRC-107.
  20. xema77

    Pretensioning of Anchor Bolt

    I agree that preloading (pretensioning) of vessel anchor bolts to a specific percentage of yield, for the reasons described above, is seldom done. It has been my experience however, that larger diameter vessel anchor bolts are tightened as much as possible using a hammer wrench or snipe. This...

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