08. Per the Flexible Joint online help, how to perform a "rigorous pressure extension analysis" in A

Applies To
Version(s):2004, XM, & V8i
Area: Modeling
Original Author:Bentley Technical Support Group

Dec 2014, AutoPIPE V8i


On the flexible joint dialog screen, "Pressure thrust area"

From the online help:

This is the effective cross section area, usually based on the mean diameter of the convolutions of the expansion joint. It is multiplied by the internal pressure to obtain the axial thrust due to internal pressure. This thrust is used if a rigorous pressure extension analysis is requested."

If I understand this text correctly, this thrust means a force that has to be applied to the pipe at both ends of the expansion joint due to the pressure in the pipe. The direction of this force is axial and away from expansion joint. Please confirm my understanding.

Also,  how do perform a "rigorous pressure extension analysis" in AutoPIPE


Correct - a force is applied in each direction.

From AutoPIPE online help on "Pressure Trust Area" (given above), Mean Dia dimension shown below:

Some flexible joint manufactures (i.e. Senior Flexonics) refer to this as the Effective Area and readily publishes these values in their catalog or project data sheets sent to their clients:

Otherwise, entering 0.00 in the Pressure Thrust Area effectively removes the Press Trust load from the model and will be ignored during the analysis which may now contain unconservative results.


1. When a flexible joint is added t a model, it is suggested to also consider axial Pcase in Sus, please see the following AutoPIPE help section:

Help > Contents> Search Tab> enter "rigorous pressure" (include the quotes), press List Topics button, double click on the "Include Axial, Pcase in Sustained" topic from the list provided to see more information on this option.

2. Suggest contacting a about a flexible joint / bellows / expansion joint manufacture and requesting some literature or catalog which would contain valuable information  (i.e.   Pressure Thrust, Pressure Stresses, Squirm, Cycle Life, Multiple Ply Construction, Applications, etc..). 


See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

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