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By: FlowGuard on Dec 14, 2021 6:33:47 AM
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Pipe Expansion Compensation Explained

No matter what piping material you specify for a project, there will be fluctuations in temperature. This naturally causes expansion and contraction in piping systems. The longer the piping run, the more the pipework will shift as it expands and contracts, so this must be compensated for in the design and installation of the system

Reducing the risk of thermal expansion on pipework reduces long term damage, leaks and ultimately, costly repairs.  Properly designed and installed features such as changes in direction, offsets, and expansion loops will flex to absorb the thermal expansion without exceeding the long-term strength of the material.  Without proper expansion compensation, the system will flex at the point of least resistance in ways which could exceed the material’s long-term strength and cause it to fail prematurely. 


The following are best practices for accounting for pipe expansion, to share with your team of installers.


The Expansion Calculator  

While designing the system and budgeting for materials, we recommend using the FlowGuard CPVC Pipe Expansion Calculator to determine the dimensions required (“L” in the following diagrams) for offsets and expansion loops. Accurate and sensible spacing and placement of hangers together with proper solvent cement installation of FlowGuard pipe and fittings, can maintain a long service life in any plumbing installation.


Change in Direction

In a typical residence, plumbing systems normally require many changes in direction; this is an opportunity to account for thermal expansion in the piping.  Proper placement of hangers will allow the system to flex properly as it expands.  Note also that the heel of the elbow must not be butted up against the structure, to allow room for the long run of pipe to expand.



Expansion Offsets

Offsets are often incorporated into piping systems for avoiding obstacles. Proper sizing of the offset and placement of the hangers will allow this configuration to flex properly as the pipe expands.  As with changes in direction, the elbows in the offset must not be butted against the obstacle or the structure, to allow for movement of the pipe.  


Expansion Loops

Where space allows, expansion loops are an effective way to account for movement, by incorporating a “U” shape into the middle of the piping run. Note that the hanger in the center of the U shape should fix the pipe in place, while the hangers on the pipes leading into the U shape should allow for free movement of the pipe.


Expansion joints are specially designed piston or bellows types of devices which compress to absorb expansion of the piping.

To learn more and to see these techniques in action, watch our new installation video series, including our video on How To Account For Pipe Expansion In Plumbing Systems.