What is a pipe expansion joint?

What is a pipe expansion joint?

Expansion joints are installed in the piping system for several reasons. They can be used not only to absorb vibration and shock, but also to relieve anchoring stress, reduce noise and compensate for misalignment. Some expansion joints are also designed for thermal expansion in very hot applications.

The expansion joint allows the pipe to move in three different ways:

Axial compression or extension

Lateral offset

Angle deflection

They usually come in three different materials to cover a variety of applications.

Metal-metal expansion joints are primarily used in applications for thermal expansion problems. As the pipe temperature increases, the metal expansion joint compresses to compensate for motion, eliminating stress from the bolts and pipes. Metal expansion joints are a prime example of how to handle expanded heat pipes.

Rubber - Rubber is used for thermal expansion and it also absorbs vibration and shock waves very well. This is why this type of expansion joint is very suitable for reducing the transmission of noise, vibration from other equipment to protect the pump and other equipment. They can also be used as shock absorbers to minimize water hammer, pressure fluctuations and trauma caused by seismic events (not that we have had many earthquakes in Wisconsin...).

Weaving - Braided stainless steel hose with flexible or metal lining is not technically a type of expansion joint, but a flexible connector. They are suitable for high pressure and high temperature applications where vibration damping or pipe misalignment is required.

These are commonly used in pumps and other equipment to help eliminate thrust loads on equipment nozzles due to thermal expansion. Eliminating the load is critical to pump performance.

The braid provides lateral angular motion. They also absorb vibration well.