Hello friends.

Please, I need some help about, how to properly model a expansion joint in Caesar II, I´ve read in help archives, when a ruber expansion joint is modeled, it`s necesary to input all the data required, I assume that is the same with a non metallic expansion joint, in the other hand, I was read that pressure thrust doesn´t apply to this kind of expansion joint, if there aren`t bellows, ther is not pressure thrust, am I alright???

Thanks

Luis Felipe Cadena A.

Hi Luis Felipe Cadena A.

You are right for ruber bellow all the stiffness data need to enter in Caesar.
Pressure thrust need to consider for any kind of expansion bellow including ruber bellow.

In fact pressure thrust is present in any piping piece & longitudinal stress is develop due to pressure thrust.
Sustain stress we calculate there is one part longitudinal stress, due to pressure. That's why if pressure is increase sustain stress is also increase.

Regards

Habib

Thanks shr,

Anybody know where can I find information about stiffness for non metallic expansion joint, specially, canvas.

Habib I supose that I need the effective area for any kind of expansion joint in order to Caesar II calculate Pressure thrust??

Thanks

Hi Luis Felipe Cadena A.

Yes bellow vendor must indicate effective area or effective ID.

Luis Felipe,

If you need info about stiffness in rubber expansion joint, I can help you...
send me a mail.

Hi aLoNsO

Really I don`t need stiffness in ruber expansion joint, I need help to model a fabric expansion joint, canvas, so if you have some information about stiffnes to this case, I really apreciate it.

if anybody has information about that, please send me a e-mail.

Thanks for the help

I would say the stiffness values are very very low. There are some semi stiff constructions but you might have one fabric only. I would enter about the lowest values the program will accept.

You need to make sure that you do not exceed the maximum movements given. If you do the compensator will be destroyed.

Jouko:

And how can I know the maximum movements for a fabric expansion joint, I supose, I can assume it, so in the data sheet that I send to provider, I have to consider this, am I alright??

Thanks for the help..

The vendor will supply maximum allowable movements for fabric bellows. Be sure to ask whether allowed movements apply acting simultaneously or only in one direction.

You will probably not be able to get anything like a spring rate. I would recommend using nominal values, just to allow a Caesar geometry model to find some stiffness.

Make sure you do not forget the pressure thrust. What cross section to use depends on required movements and the design your supplier is using. Supplier will add enough fabric (up to a point) to achieve required movement. Best is to ask the cross section value from the supplier.