Dear all,
Can anyone please tell me why we getting two code stress in both static and expansion cases.

Ujjwal Kundu

Do you mean a different maximum allowable in sustained and expansion case?
That is cause the code requires so. Sustained = primary stresses, expansion = secondary stresses.
This is the basis for pipe stress analysis. Please make sure you understand this before making any analysis. And contact a senior engineer for a lot of explanation.

Please read the "sticky topic" on Allowable Stresses at the top of this Forum (it's the 3rd one from the top).

Ukundu,

Are you talking about having two sustained cases and two expansion cases?

This will happen if you have inputed two temperatures and two pressures in the spreadsheet (probably your operating and design conditions).

If not, be more specific. Or, read some text and books before proceeding with your job.

Goodluck!

Dear sir,
I am not giving two pressure temparure case,i give only one pressure and one temparature and also give hydro presssure.But getting two different values of sustaained load case for some nodes,not for all the nodes.same thing haappening for expansion case also.
I can aattaching the model beacuse i dont getting link to attache or i dont know how to attach a file in this reply.

Ukundu

Ok, try this ....

Your piping system is a series of elements, connected by nodes, as in:

10-------20-------30-------40--------50-------60 etc.

If you look at the elements individually you see this:

10-------20 20-------30 30-------40 40--------50 50-------60 etc.

So in the "Element Force" and "Element Stress" reports, you see data associated with each element. As the sketch above indicates, there will be two node 20's, two node 30's, etc. Yes they can each have different values, as long as both the element and the node are in equilibrium.

Note that when you have a tee, as in:


node 110 will appear in the reports 3 times; once for 100-110, once for 110-120, and once for 110-710.

I hope this answers you question.

Thanks Mr.Richard Ay for your nice answer.As you give me an example of tee of node no 110.Can i get three different vlue of stress for same node no 110 for the three "Element Stress"(100-110,110-120,110-710)?If so then how it possible to remain in equilibrium.Please help.

Thanking You
Ukundu

Sorry to interrupt ....

Dear Ukundu,
You have to learn the finite element method for the beam element. The equilibrium is the forces & moments at the same nodes if you sum it. These F and/or M at each nodes then used to calculate the stresses.

Try the formula in CAESAR II.quick.pdf for ASME B31.3 to calculate the SUS stress...from the global element force (FX, FY, FZ, MX, MY, MZ) report see which one axial force, inplane and outplane bending moments,consider the SIF & internal pressure. Substitute that to the SUS stress formula. Good luck...

And please note that when you calculate SUS stresses at nodes, you have to use global element forces report from SUS case too. It is the same also for others cases.

Dear Samsul P. Manik

thank you very much.

Ukundu