Pipe Guides and Anchors

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Do I really need anchors for this expansion joint?

Yes you do. See, “How do I calculate in line bellows anchor loads.”

How do I calculate in line bellows anchor loads?

It is common mistake to underestimate the anchor loads developed by an inline bellows joint.  This is the case for both internally pressurized and externally pressurized joints.  For inline bellows joint, the anchor load can be calculated by adding the three major loads together.


Pressure Thrust  Pressure X effective area (Use the highest pressure possible, often the test pressure). The effective area of a bellows is often overlooked.  The effective area can be found by calculating the area of the “mean” diameter of the bellows.


Deflection Load Published Spring Rate X movement of the joint. The deflection load is the force it takes to bend the stainless steel bellows


Frictional Resistance   Total weight of pipe, media, insulation X .3 coefficient. The frictional resistance is the force it takes to overcome the friction of any hangers and guides in the piping system


For the effective area and spring rates vary from joint to joint.  You can find the data of each joint with the bellow links.



HP Compensator 3” Axial

HP Compensator 2” Axial 

HPFF compensator 2” Axial

HPFF compensator 3” Axial

How many anchors do I need for my thermal expansion application?

The rules are:

1. To divide up the piping system into the largest sections a single joint can handle

2. Place anchors between the joints.

3. Review that the anchor locations are suable for the installation of an anchor. In line bellows expansion joints can develop high anchor loads.  See How do I calculate in line bellows anchor loads?

4. Only install one expansion joint between anchors.


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