Yeap Dan, I agree with you, but what do you think about that:

"Manufacturers publish a wide variety of data for universal expansion joints. In most cases the published spring rates are for the universal joint as a whole assembly. When the lateral stiffness is given for the whole assembly the simple or complex models of single bellows can be used. In this case the manufacturer must also provide a cumulative assembly displacement limit so that the piping designer can verify that neither of the bellows are over-extended".

It's my doubt, because I read it on CAESAR manual...

Could somebody explain me it ?

Thank you very much again.

Best Regards,

Saulo Cunha