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Expansion Joint

Expansion Joint

Expansion Joint


I just want to ask regarding the stress analysis for a single expansion joint (without the tie rod). Is it always required to provide anchor support near the single expansion joint (without the tie rod)?

Thank you in advance.



RE: Expansion Joint

Well if you don't there isn't much need for the expansion joint and it becomes difficult to calculate.

You need to give us much more here to work with - a drawing / sketch, isometric, size, movement, why you think it doesn't need one, why you're putting an expansion joint in in the first place etc

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Expansion Joint

What is going to absorb the pressure thrust if there is no anchor??

RE: Expansion Joint

Actually the line is an existing 60" (reducer 66"x 60") pipe that is connected to a centrifugal pump. The main problem that I am facing right now is the type of expansion bellow used in the site because in the datasheet of the designer the 3rd expansion bellow (see the attachment for the illustration) is a hinged type EJ while the existing or as per as-built/site the EJ is only single EJ (without any tie rod /hinge). Upon analyzing it in the CAESAR II, if the 3rd EJ doesn't have tie/hinge there is a big displacement along the line going to the elbow (-Z) that will also result for stress-over.
Additionally, I cross-checked the latest isometric versus the as-built/site condition, there is no anchor near the 3rd EJ (except the pump nozzle).
I just want to clarify for the need of an anchor near the single EJ, Is it really needed? If yes, why the as-built doesn't have anchor and yet the line is still operating?

FYI: Temperature : (Ope) 50C & (Design) 90C
Pressure : (Ope) 6.5 bar & (Design) 10bar
Line size: 60" (reducer 66"x 60")
Maximum Displacement in the 3rd EJ = approx. 2300 mm (if no tie/hinge)
Maximum Displacement in the elbow = approx. 150 mm (if no tie/hinge)
The displacement above is very large.

Thank you in advance.



RE: Expansion Joint

It seems that the existing pump discharge piping is installed not based on the design. I wondered it's because of the change after the original design was done but not properly documented.
IMO, the support is needed next to the EJ which is designed for the movement but not the weight support. Per attache stress iso, are the nodes #54 and #90 for the pipe supports adjacent to the EJ's?

RE: Expansion Joint


Node 54 has no other purpose and removed after my final report while node 90 is an immediate spool after 3rd EJ that is connected to the reducer.

RE: Expansion Joint

IMO, without the proper weight support or lateral guide, the whole pipe section and three EJ's will dangle in the air. Since the piping system is in service, you may verify if a proper inspection plan is in place for the EJ's pipe section, or if it needs one just in case.

RE: Expansion Joint

A vertical circular "piece" 702-30 is welded (somehow) to the bottom of the hirzontal elbow at the corner, and has a 12 mm (1/2 inch) plate welded to the bottom of the vertical member. So, there is vertical support at the corner between two of the three expansion joints.

But, is that plate sliding on something fixed but with no resistance, welded or bolted firmly to something fixed (like an anchor), or is the 12 mm plate merely assumed to be sliding around on a "perfect surface" until rust and crud freeze it solid?

RE: Expansion Joint


The dummy you are talking about is sliding/not fixed. I already checked it in the site.

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