×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Nozzle Load on FULL VACUUM Vessel

Nozzle Load on FULL VACUUM Vessel

Nozzle Load on FULL VACUUM Vessel

(OP)
How do you check the nozzle loads using WRC 197 / 297 for nozzles on a vessel operating at Full Vacuum?
The worst case would be a radial (axial load) pushing into the vessel.
How is the effect of vacuum taken into account?

RE: Nozzle Load on FULL VACUUM Vessel

Take a look @ Gilbert & Polani's "Stability Design Criterion for Vessels Subjected to Concurren External Pressure & Longitudinal Compressive Loads" ASME Trans Jnl PVP May 79, Vol. 101 pp178-81.

 

RE: Nozzle Load on FULL VACUUM Vessel

The way I understood it was that you can plug in the vacuum pressure as internal pressure but reverse the signs for the pressure stress when superimposing the stresses from the applied local loads with the pressure stress.  Any comments on this method?

RE: Nozzle Load on FULL VACUUM Vessel

PV Guy, I see two possibilities for problems.  One is, if the method used for checking stresses does not check stresses at every point, but only at the point where the maximum is expected to be, then you could miss the maximum stress.  And secondly, if in some way, the load was limited by buckling rather than by yielding, you could miss that.  Otherwise, the stresses should be workable as you suggest.

RE: Nozzle Load on FULL VACUUM Vessel

JStephen get a star for that one.

Steve Braune
Tank Industry Consultants
www.tankindustry.com

RE: Nozzle Load on FULL VACUUM Vessel

Thanks JStephen,  forunately I use the original which checks stresses at all the points.  Also if the total stress is negative I use the allowable compressive stress by the code (UG-23).  Is that what you meant when talking about buckling?

RE: Nozzle Load on FULL VACUUM Vessel

If you have a pressurized vessel, and apply an outward nozzle load to it, you'd just check allowable stresses.

If you have a vessel with vacuum, designed for that vacuum, and you apply an inward nozzle load to it, the nozzle load could act with the vacuum load to buckle the vessel.  And that type of failure is not anticipated in the usual nozzle stress calculations.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources