Analysis of rubber Expansion Joints

Hi,
I would like to analyse a Rubber Expansion Joint which is located on a FRP Line.

Pl. let me know how to analyse the same.
Thanks - Nitin

Hello,

Well, Do you really want to analyze an elastomeric expansion joint or do you want to analyze a piping system that includes an elastomeric expansion joint (EEJ)?

Assuming the latter, I don't see much difference in the analysis techniques required for systems including various expansion joints be they metallic or elastomeric. There is a wealth of information available in the Caesar II (C2)manuals which addresses this topic.

Of course the first thing you will want to do is check with the manufacturer of the EEJ to make sure it is appropriate for the temperature and pressure of the piping system in which it is intended to be used. Since the system is FRP, it is likely that the EEJ will be OK (assuming the FRP is appropriate). Then all the warnings provided in previous threads regarding expansion joints apply. Remember an EJ is one third of a system (anchors and guides are also needed). Remember that an expansion joint is a (beam)discontinuity in the pipe it is installed in (in many regards, the EJ "disconnects" the two ends of the pipe that are connected to it)and hangers will be needed on both sides of the EJ. Your system will have equal and opposite "bore thrust" forces applied (away from the EJ) since the EJ is a discontinuity in the pipe wall (see Dave Diehl's comments in earlier threads - Rich, can you supply a path?). Finally, be aware of the EEJ's limitations regarding total travel.

Regards, John.

There are twelve (12) different discussion threads in this forum dealing with expansion joints. The best way to review these threads is to use the <font color="#0000ff">search</font> option of the <font color="#0000ff">my profile|register|search |faq|forum home</font> control in the upper right corner of the forum.

John is correct though, there should be no problem modeling this type of expansion joint, assuming you acquire the necessary stiffness parameters from the vendor, and you watch the limits.

Expansion joint stiffness data in terms of trasverse and rotational stiffness can be obtained from vendors.This data can be used for modelling the expansion joint.The forces and moments obtained based on analysis(dead weight,thermal,seismic or spectrum etc.,) must be forwarded to the vendor for qualification of the Expansionjoint.Only when both Piping and expansion joint are qualified we can conclude that system is safe.

I agree with the comments given by the Moderator

thanks

c srinivas