×
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

Stress Analysis of Vibrating Pipework

Stress Analysis of Vibrating Pipework

Stress Analysis of Vibrating Pipework

(OP)
I am currently reviewing a process pipe system used to blow a slurry from the bottom of one vessel to the top of another.  The system historically has had a problem with vibration primarily caused by the density variations in the slurry caused by the motivating fluid - steam.  

Does anyone have an idea of how this can be modelled in AutoPIPE (or similar) to ensure that the line is not overtsressed and has a reasonable design life?

I have considered applying a force acting perpendicular to the pipe at the mod point of the bend,  however I am unsure of what magnitude this should be.  Is this the correct approach?

Any assistance is appreciated.

Regards

RE: Stress Analysis of Vibrating Pipework

Possibility is using BOS FLUID for more information on the  videos clip go to boss_steam_hammer  

http://www.paulin.com/   (download), (left side VIDEOS)

RE: Stress Analysis of Vibrating Pipework

Your best bet is going to be to get field measurements of the magnitude of displacement at a few points of the line as it is shaking.

From there, you can check the stress value due to the displacement and see how many cycles that stress level is good for.  You want the displacement to be small enough so that your cyclic stresses are low enough to allow "infinite" life.

Quite frankly, I can't tell you the details of how to make the check.  Other guys in my department are fluent in the specifics and I've not had the opportunity yet work such a problem.  I would recommend posting this to the Caesar II forum over at the COADE website to get some pointers to references to consult.  Messrs Breen, Luf, Becht, and others can no doubt point you in the right direction.

Now, all that said, if you can clamp it down to damp out the vibrations w/o imposing excessive thermal stresses, that will be the way to go.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

RE: Stress Analysis of Vibrating Pipework

In Algor's pipepak you can apply a time history load to nodes. In order to determine the load you would need to do a transient analysis or some other calculation.

Initially the software undertakes a modal analysis to determine the natural frequency of the pipe for different frequencies. The time history load is applied and the dynamic response of the pipe is reported graphically or by dynamic image.

The problem comes about in the couplingof the fluid model to the dynamic structual model. There are quite  few papers covering fluid structure interaction and the debate that still rages on how to do this accurately.

Look for papers by Wachel on vibration analysis and measurement www.engdyn.com/papers/papers_table.htm

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