Flange Loading 2

[pipesvessels1]

All,

Is it possible to get the specific Flange loading at joints in piping system from CII to use for comparison with Allowables?

Any thoughts appreciated,

Cheers,

JOD

 

[MJCronin]

John..

Why are you doing this ??? Is the qualification of individual flanges within a piping system your idea, or do you have an MBA as a boss ???!!!

I have only heard of a flange/moment investigation when the individual flanges were leaking, and in every case there were installation problems (ie wrong gasket, excessive cold-spring)

The internal forces/moments of the system are available from the CAESAR-II output...

MJC

 

[pipesvessels1]

Thanks MJC,


CII does give the results but it can take forever to pinpoint which particular Flange is most heavily loaded. I'm trying to identify highest/worst case forces and moments for each size of Flange in the piping system and then check to see if flanges acceptable under these worst loads?

Cheers,

JOD

 

[NozzleTwister]

JohnOD,

In CAESAR II, you can model an Anchor with a CNODE at the flange faces and your flange loadings will be listed in the restraint and restraint summary reports so you would have to wade through all of the elements shown in the force and moment report.

In my industry it's common to evaluate highly loaded, high temperature flanges for possible leakage due to high bending moments. CAESAR can do this analysis for you. Under the Analysis tab, click on Flanges and input the requested data.

Good Luck,

NozzleTwister
Houston, Texas

 

[pipesvessels1]

Thanks Nozzle Twister,

Yes I am aware of the Flange Module in CII. In this module there is an option to enter an Axial Force and a Moment. These are precisely the values I am seeking to find, well, the worst case of anyway. However, with say, 15 Load combinations on a large model, to pinpoint the most heavily loaded flange is tedious to say the least.

With regard to the Anchor/C-Node, won't this change the whole 'balance'of the piping system?

Cheers,

JOD

 

[NozzleTwister]

JohnOD,

"With regard to the Anchor/C-Node, won't this change the whole 'balance'of the piping system?"

ABSOLUTELY NOT! ....if you model it correctly. C-Nodes are a wonderful thing. They allow you to call for an anchor where you need loads for equipment nozzles (your case flanges) and keep on coding the equipment or other piping. It's best to see the CAESAR Help Manuals, C-Nodes have other uses that I haven't mentioned.

Your coding for your flange (simplified) would look like this:
10 to 20, say X=5in, RIGID=120lbs, Anchor 20, CNODE 30
30 to 40, X=5in, RIGID=120 lbs
40 to 50 ..... and so on.

You can also add a short pipe element beteewn the flanges (I use the gasket width) if you want to see stress at that point.

The beauty of the C-Node is that you will get anchor loads on your restraint summary, but this anchor will discplace and rotate with your system.

Your analysis, stresses, displacements, restraint loads and displacements should be EXACTLY the same after you've added the C-Noded anchors. If they are not, there is an error in the coding.

Good Luck,

NozzleTwister
Houston, Texas

 

[MJCronin]

Nozzletwister,

I am very curious about your need for this type of evaluation..... You state:

"In my industry it's common to evaluate highly loaded, high temperature flanges for possible leakage due to high bending moments.."

What industry are you in and what do you do with this loading information once it is developed ?

What criteria do you use to distingush between "possible leakers" and safe flanges ? Is this an "in-house" developed criteria ?

Are there any references/websites that you can point me toward ?


regards....

MJC

 

[NozzleTwister]

MJCronin,

We do engineering design for refineries.

You might find the thread below from COADE's CAESAR II forum helpful.

http://www.coade.com/cgi-local/ultimatebb.cgi?ubb=get_topic;f=1;t=000923

We do engineering design for refineries.


NozzleTwister
Houston, Texas

 

[MJCronin]

Nozzle...


Thank you very much for this link !!

-MJC

 

[NozzleTwister]

MJCronin,

You're welcome!

NozzleTwister
Houston, Texas

 

[StressGuy]

MJCronin,

I must admit, I'm now curious what area of the business you are in. Flange bending loads are a pretty common item to check as part of a piping flexibility analysis for those of us working in the design of refineries and chemical plants. I was quite surprised at your initial post above that seemed pretty dismissive of JohnOD's concern.

And yes, CNODES are your friend. 1001 uses.

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.