Modeling of expansion joints in CAESAR II 1

[B.L.Smith]

Hi
1- What should I choose material of a Rubber expansion joint in CAESAR?(In CAESAR database is not materials for rubbers.)
Is there any guide documents(exclude COADE DOCs) for modeling of expansion joints in caesar?
2- I have a tied rod EJ with outer nuts. Can I leave blank Effective ID and exclude modeling of rods?

 

[B.L.Smith]

another question:
3- Why in 5-6 and 5-8 of caesar applications guide Effective ID are not zero or blank?(But in tied rod expansion joints pressure thrust acts on piping is zero.)

 

[richay]

1) The CAESAR II expansion joint databases only contain manufacturers data for metallic bellows. For a rubber joint, you'll need to obtain the stiffnesses directly from your vendor.

2) Yes but it would be informative to obtain the loads on the tie-bars. It will only take a couple of minutes to model the tie-bars, and you'll have a better model.

3) Well, as long as the tie-bars are properly sized, they will take the pressure thrust load from the piping. But what if they aren't properly sized...

In summary, you want the best, most accurate model you can define, because there are other unknowns in play, some of which you may not know when you start. Why take the risk with an inaccurate model to save a few minutes of modeling time?

Richard Ay
Intergraph CAS

 

[B.L.Smith]

Thank u Richard Ay
4- Does pressure thrust act on nozzle and nozzle must withstand this pressure thrust?

 

[B.L.Smith]

5- In Rubber Expansion joint with one arc, Is pressure forces balanced?(i.e. effective ID= pipe OD)???

 

[richay]

4 - Maybe, it depends on they system configuration and the associated restraints.

5 - Probably not (but I don' personally have experience with rubber expansion joints). Ask your joint vendor.

Richard Ay
Intergraph CAS

 

[B.L.Smith]

Dear Richard Ay,

Can u explain more about (4)?
And I think according to the attached file page 2, there is pressure force balanced in a rubber expansion joint because the pressure on the right hand of the rubber arc is balanced with the left side also the effective ID=pipe outside diameter. Thus we don't need to ask effective ID from vendor. Are you agree with me Mr Richard Ay?

 

[richay]

Open a Support Request in eCustomer. We can send you a document that explains our rationa.

Richard Ay
Intergraph CAS

 

[B.L.Smith]

please clarify:

The attachment is from Peng handbook(pipe stress engineering).
Is this lateral expansion joint ? why does it mount in a line which can not move laterally?