We have large number of rubber bellows of filled arch type used for compensating axial compression movement with high 10 bar design pressure. Failures are recurrent in such bellows having control rods. Is the configuration not foolish enough! Can rubber withstand high thrust in operating condition with inactive control rods ?
Reg

In expansion joint, the pressure thrust is the gauge pressure times the area within the mean diameter (Dm) of a bellows. Where mean diameter is internal diameter of bellow + effective diameter of bellow convolution or “Arch”.

By using filled arch, pressure thrust due to effective area of arch can be reduced but system needs to be designed for thrust due to internal diameter ie Pressure* pi()/4 *ID^2. Please correct me if my understanding is wrong.

Yes. Your understanding is right. But, reason of providing filled arch is different ..not to reduce pressure thrust, but to avoid accumulation of material inside pipe .. mostly powder.
This wrong configuration of putting untied bellow in compression duty with control rods originate from the wrong presumption that till control rod comes in action, rubber will withstand longitudinal tension of high design pressure.

Unless the basis is right, application fails!
Reg
Sam

If the joint is installed correctly and the joint is compressed, how is longitudinal pressure stress causing your joints to fail?

Check the as-installed alignment and face-to-face distance. Make sure the outside nuts are tightened so the joint cannot extend and secured (tacked? double nut?).

During operation, check the alignment again and the displace face-to-face dimensions. Note gap on the outside nuts.

A facility in a very sunny location lost dozens of rubber expansion joints because the installation contractor failed to provide the anchors and guides called for by engineering. They also bought the cheaper non-UV resistant rubber and neglected to apply the recommended coating.

I agree Steve. Who knows the real situation in field?

It sound that it is an improper use of the bellows. 10 bars is ok.

Sam, please try to describe well the situation, people do not know all details.

We, stress(ed) people need a lot of info. Otherwise we only guess.

If bellow with 100% coldpul can really withstand high pressure integrity using control rods as is the priciple behind the 1997 pta blowegg rubber bellow design, we would not need any pressure balanced bellows or tied/hinged bellow arrangements in case of metallic bellows in the first place.

In fact, rubber bellows are in gasious/solid service, where small leakage may be permissible at times of high pressure.

It is not easy to determine exactly when rubber bellow cold pull compression is fully released under pressure and before it is tension, rubber bellow control rod nuts need to prevent further expansion; any small play in the control rod nuts can cause pressure integrity.

It might be popular in use, but not safe and sound enough in principle where leakage can cause loss of production!

Flex hoses at these locations could have been much better choice!
reg,
sam

rubber bellows are to be used in compression (tie-rods sometimes only for safety) or for lateral movements, vibration control. If used for other purpose, this need to be discussed with vendor. Some are special reinforced in order to take also some thrust.
There are some limitations for rubber bellows but are not so bad. Also filled arch are used for slurries.