Pipe Crossing Building Expansion Joint

[NickDePinho]

Hello I am modeling a 16" HW pipe crossing a building expansion joint. There is movement in the X,Y, and Z direction.
Due to both coordination & cost the owner does not want to use a product to take the minimal movement and instead wants the pipe geometry to take it.

I believe this is fine. I am currently running a pipe stress analysis on caepipe. My thoughts are to use the natural geometry as pipe as a Z bend and anchor the pipe on both sides of the building expansion joint. Then I am going to put displacements in the thermal load on the anchors on caepipe (I believe this is the best way to model it)

Curious how people have handled building expansion joints in the past.

 

[KevinNZ]

Depends on what building load cases the displacement across the building expansion joints. If thermal movement then you can include this in the thermal expansion range of the piping. EQ loads (or wind) opening/closing the gap will need SAM modelling for the piping.

 

[Flexatherm Expanllow]

Hello,


Thanks for sharing your approach—it's always good to see detailed consideration being given to expansion joint crossings.


While modeling pipe geometry to absorb movement can be effective in some scenarios, it's important to keep in mind that relying on the pipe's flexibility (like using a Z-bend or offsets) to accommodate multi-directional movement across a building expansion joint has its limitations. This method introduces additional stresses into the system, and depending on the magnitude of movement and the pipe material, it may not provide long-term reliability or sufficient fatigue resistance.


At Flexatherm, we typically recommend using engineered expansion joints specifically designed to handle thermal and building-induced movements. These products are tested and validated to absorb movements in X, Y, and Z directions while minimizing stress on the piping system and connected equipment. Additionally, they often result in more compact and predictable designs compared to long flexible loops or Z-bends.


That said, if your CAEPIPE stress analysis confirms that the induced stresses remain within allowable limits per code (e.g., ASME B31.1 or B31.3) and the expected movements are minimal, your proposed solution could be acceptable. Just ensure that the anchors and guides are properly designed to handle the resulting loads.


If you’re interested, we’d be happy to review your movement data and offer recommendations on suitable expansion joint solutions that align with your coordination and cost constraints.