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  1. alanw7272

    Large Rectangular Door in Ellips Head

    Crompto29, May I ask why? Why not use a standard circular manway? I have only seen rectangular openings in the shell section before, not a dished head and especially not the knuckle region. Also you cannot simply treat this as a circular opening to Code Rules. You are going to have high stress...
  2. alanw7272

    Filling vessel with Nitrogen

    Teokal, 0.1 barg sounds a little low. In all likelyhood the nitrogen will leak slowly, especially when the vessel is transported. Thus it will need to be topped up more often once the pressure has fallen! On what basis did you arrive at 0.1 barg? ie: is this vessel rather large? We are doing...
  3. alanw7272

    Butane as a blanket gas?

    Not sure on the reason for blanketing fuel oil but I have seen gas used as a blanket where nitrogen was not available. Still better to have a gas blanketing than air! Is the tank in a remote location?
  4. alanw7272

    Nozzle Loads + External Pressure

    JStephen, I kinda agree with you but am also not sure that a radial load on a nozzle, acting inwards, contributes to buckling in such a simplistic manner. Typically these loads are thermally produced and cause secondary stresses local to the nozzle (as you said). It tends to be requested but I...
  5. alanw7272

    Nozzle Loads + External Pressure

    Hi Lee, Yeah this is a common request to check the radial load as a positive and negative value, ie: acting outwards and inwards. You can check this simply by changing the radial load sign in whichever program you are using, WRC 107 / 297 / App.G, however just watch the directions as they all...
  6. alanw7272

    TEMA / ASME Backing Ring

    Thanks for your reply DG72, I have reviewed the interpretation in TEMA and understand their thinking. However I think PD5500 uses double the moment for flange stress! Guess its a bit open to interpretation! I just would have expected TEMA to be a bit more precise with their calculation or at...
  7. alanw7272

    TEMA / ASME Backing Ring

    Hi, TEMA RCB-5.14 has 4 different configurations for a backing ring, type S. The TEMA equations suggest that for Styles A, C and D you can use the bolt load 'W' and for Style B you must use the bolt load '2W'. I understand the 2W as Style B is split, but then so is Style A and D. I am using...
  8. alanw7272

    bundle runners / rollers / ?

    Hi, I am designing some large helix exchangers with bundles in the region of 44 tons, 1900mm diameter and 8200mm long...some pretty big buggers! Does anyone know of guidelines or have any practical experience for when to change from bundle runners to say bundle rollers? API 660 Annex A does...
  9. alanw7272

    Stress Ratio for Calculation of Hydrotest Pressure

    I've seen it done both ways for exchangers. Client specifications sometimes do not allow the use of bolting to check the stress ratio. I know of no limitation in the Code. When I design exchangers, I do not consider bolting as I believe this to be the norm. Why do Vendors fight this? Its simply...
  10. alanw7272

    WRC107 in Codecalc

    Thanks for your reply L S THILL. Forgetting FEA for the time being and focussing on WRC107, I understand from your reply that you only check the final stress results (Pl+Pb+Q) regardless of the imposed loads being sustained or expansion related? From reading Appendix 4 of ASME VIII Div.2 I...
  11. alanw7272

    WRC107 in Codecalc

    Hi, I notice in Codecalc WRC107 they have now included a 'stress summations' box in which the software shows resultant vessel stress and a 'passed' or 'failed' result. This is great as in a glance the engineer can see whether the vessel stress is acceptable, or can they? I do not think these...

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