Expansion Joint Tie-Rod Gaps

[tsarbomba_imported]

Can anyone explain what is the meaning of tie rod gaps provided by the manufacturers?
What happens when there is no gap in either one of forward or backward direction?
What happens when there is no gaps at all? If there is no gap, will it help the piping system in reducing axial load? and how?
Is expansion joint not useful in tension case?
If the gaps are fully closed due to expansion or compression, what impact will it have in the system?
When the forward gap and backward gap is not fully closed, is the use of expansion joint justified?
I am bit confused about the tie rod used in expansion joint. So can anyone clear few queries that I have. I will be very thankful for any answers.

 

[Ehzin]

This will only answer a portion of your question. Sometimes expansion joints with no tie rod gaps are used for very large exchangers. If I have a 30+ foot exchanger with a design temp of 300 °F and the channel end is on the non-anchored or floating side it could want to grow around 1/2" away from the anchor point on the other side of the exchanger. If I have a 30" Std. cooling water line 6' long leaving straight from the channel going directly down into the ground it would normally cause MASSIVE loads due to the top connection wanting to drift 1/2" and the pipe having essentially no flexibility. One easy fix is an expansion joint that has double locked tie rods. The joint doesn't need to accommodate any axial movement itself it just has to handle the axial movement of the exchanger. Therefore it has a fixed length due to the "no gap" tie rods but it will allow the ends of the expansion joint to move transverse to each other (There will be some gap but it's really only to allow for transverse movement of the joint).

So that combination of run on sentences was just to show one use of expansion joints where there's no real axial displacement of the joint. If it needs cleaning up just let me know and I can work on it.

Thanks,
Ehzin

 

[tsarbomba_imported]

Thank you very much for the reply.
It is of great help for me to understand things about Expansion Joints.

 

[europipe]

There is a lot on the net.
Google can do a lot.
P.E. :

http://www.witzenmann.be/be/media/Expansion_joint_manual_1501uk_5_12_12_20_download.pdf

http://www.ork-flex.com/catalog/pdf/e-catalog4.pdf