×
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 Differential Pressure

Nozzle Differential Pressure

Nozzle Differential Pressure

(OP)
I have a vessel at pressure 4 bar.

A nozzle passes through the wall of this vessel.  The pressure inside the nozzle pipe is 7 bar.

What pressure do I use to design this nozzle?

I would like to calculate the minimum thickness of the pipe on both the inside and outside at 7 bar and use the remaining pipe material as reinforcement.  Where the rest of the nozzle reinforcment is calculated for the vessel pressure of 4 Bar.

Where UG-40(d)(2) says 'differential pressure causing opposing stresses is not allowed' does it mean I now have to use 7 bar for the entire reinforcement calc including the shell minimum thickness.  Or is it just saying that I can't use 7 - 4 = 3 bar for the internal projecting part of the nozzle?



 

RE: Nozzle Differential Pressure

I use the worst case.  Ask yourself "is it possible for the pipe to be pressurized when the vessel is not?"  If so, use 7 bar.  Do the same thing for the other differential, then design for 4 bar for the vacuum calculation of the nozzle.

That is my method.  I have had AIs say that I was too conservative on the design, but I would rather be on that side of the argument than the other.

RE: Nozzle Differential Pressure

(OP)
Thanks,

I would expect if the pipe was at 7 bar and vessel had no pressure there would be no need to do a reinforcment calc.

And if the chamber was at 4 bar and pipe at zero, I would do a regular nozzle calc as though both pipe and shell were at 4 bar. (UG-40(d)(2) says 'differential pressure causing opposing stresses is not allowed')

The worst case is if the shell was at 4 bar and nozzle is at 7 bar.  How do you deal with that?  Designing the entire opening for 7 bar seems very conservative.

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