Problem:

How to model an in-line Pressure Balance Expansion Joint in AutoPIPE?

Solution:

Per the following catalog cut sheet:

See detailed approach in the attached files for modeling an In-line Pressure Balance Expansion Joint in AutoPIPE

Download File here

Comments, Questions, and Answers about this modeling approach:

Item #1: Can I model the retaining rods as actual pipe runs?

Answer:

the official answer to can it be done, Yes, it can be done. However the next question is, should it  be done, suggested answer, No.

Remember each pipe segment in AutoPIPE needs to be suitably restrained to prevent the analysis failing due to Unstable System error message.

Model tie/links as pipe: create the extension beams as outlined in the AutoPIPE example, then connect the extension beams with a pipe run.

Model retaining rods as tie-links: see AutoPIPE example - Pressure Balanced Expansion Joints for details.

Note: Beams can have a pipe shape, on the Beam Section Properties dialog specify a Pipe Section Type.  

 Item #2: Should the pressure area be set to 0.00 for all Flexible joints that make up a pressure balance joint?

Answer:

NO !. 

Suggest that the user enter the correct Pressure Area per the size of the bellows and be sure to connect the multiple bellows that make up the assembly as mentioned by the Manufacture. Most of the time the manufacture provides data on the over all joint. The model approach being implementing needs the data for each of the bellows that make up the entire assembly.

As shown / mentioned in AutoPIPE's Examples for pressure balanced joints the "Pressure Areas" are NOT blank (unless said bellows are arranged in the assembly such to not be exposed to internal pipe pressure). Again, be sure each bellows has the correct data and that the tie/link rods are connected correctly.

Item #3: Can you provide better details about the example model download above. Why there are crosses and tees modeled. 

Answer:

First take a moment to study the Excel spreadsheet that is in the downloaded ZIP file. This file has an image with related details about the modeled pressure joint. 

In addition, see the following images:

Again, review the Excel sheet for more details. This modeling approach assumes that 2 expansion joints are connected to one point.. 

Be sure to use this example as a teaching tool, your model in line pressure joint may be a little different. thus requiring a different modeling but using the same techniques here.  

See Also

Flexible Joint - Modeling Approaches, Tips, Techniques

Bentley AutoPIPE