Hi,

How do I model a tied expansion joint with lateral movements for compressor discharge line. The allowable forces is 890 lbs. and allowable moments at the nozzles is 1325 ft-lbs. I did followed the application guide and did use the 'Expansion Joint Modeler' and the result, i cannot make it work with in the allowables of nozzle. The temp of line is 257 deg F and pressure is 102 psig.

Please i need help i am having hard time making this line work.
If you have different way of desinging the expansion joint in CAESAR please advice me.

Regards,
Gaurav

Then perhaps the expansion joint isn't the solution. There is no guarantee that an expansion joint will resolve your nozzle load issues. Find the source of the high load and find a way to reduce it.

Thanks for the advice. But i would like to now how to design expansion joint using CAESAR. For my application expansion joing is the solution.

Thank you
Gaurav

Glindeep,

The goal is overall flexibility of the piping, which your expansion joint is one component. The tied expansion joint might not have enough lateral flexibility even with 12 or more convolutions. The stiffness of expansion joint increases for larger diameters to where I would prefer to use a tied universal expansion joint with pipe spool in between the two bellows convolution sections. If the pipe size is small enough (Nps-3 or less) then a metal flexible hose with overbraid cover might be the solution in place of an expansion joint.

You don't state the pipe diameter. I would suggest a length of tied universal expansion joint assembly of at least 5 times the pipe diameter, to achieve more lateral flexibility (I had used one of 54" length 4x pipe diameter Nps-12 last time). The tied universal EJ assembly would best be located where it would be perpendicular to direction of largest piping movement. It might not need to be attached to the compressor outlet. The weight of the tied universal EJ assembly could be supported by a spring hanger on side away from your compressor. You may need to revise the piping layout to fit this length of tied universal EJ assembly into the piping routing.

Look at catalogs of Pathways Bellows, or Piping & Technology Products for data on expansion joint stiffness values, and select a unit with a stiffness rate x your deflection to get less than your allowed loads.

Sites: www.pathwayb.com/Downloads/Metal%20Catlog.pdf
www.pipingtech.com/products/expjtcat/universa.htm

The CaesarII software will not select the expansion joint for you, that is something for you to select as the designer. It is not like getting a spring hanger selected by CaesarII, but involves a number of decisions by a designer. Good luck to you.