Why Do I Need A Piping Expansion Joint?

Author: Dale Annoye | May 12, 2016 | Category: Pump Piping

metal_expansion_joint.jpgThe same pump failed again. A manufacturer experienced repeated failures on the same pump over and over, and even though the pump had been properly repaired, installed, and aligned, it still experienced chronic vibration issues.

A closer look determined that the vibrations were not being emitted from the pump, instead it was being affected by vibrations from other equipment as it travelled along the pipes. What can be done to stop rogue vibrations from affecting the pump?

A piping expansion joint might help.

What is a piping expansion joint?

An expansion joint is installed in piping systems for a couple of reasons. Not only can they be used to absorb vibrations and shock, they can also be used to relieve anchor stress, reduce noise, and compensate for misalignment. Certain expansion joints are also designed for thermal expansion in very hot applications.

Expansion joints allow pipes to move in three different ways:

  • Axial compression or extension
  • Lateral offset
  • Angular deflection

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

Metal – Metal expansion joints are mostly used in applications where thermal expansion is an issue. When the temperature of the pipe increases, the metal expansion joint compresses to compensate for the movement, taking stress off the anchors and the pipe. A metal expansion joint is a prime example of how to handle expanding hot pipes.

rubber_expansion_joint.jpgRubber – Rubber can be used for thermal expansion, and it also absorbs vibration and shock waves extremely well. That’s why this type of expansion joint is great for minimizing the transmission of noise, vibration from other equipment to protect equipment like pumps. They also work as shock absorbers to minimize trauma caused by water hammer, pressure surges, and seismic events (not that we get a lot of earthquakes in Wisconsin…).

Braided – Braided stainless hoses with flexible or metal liners aren't technically an expansion joint, more of a flexible connector. They work well in high pressure and temperature applications requiring vibration dampening or pipe misalignments.

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

Braids provide lateral an angular movement. They also absorb vibration rather well.

Why would I need one?

We described some of the big reasons why expansion joints are helpful in piping systems already, but just to recap:

  • Thermal expansion of piping
  • Solve initial piping misalignment and settlement lateral offsets
  • Pump and equipment vibration
  • Shock and bending loads

Your entire process is intertwined, each piece affects the next. Having a reliable piping system is key to a process that maximizes uptime. Carefully managing your piping system not only keeps the pipes in great working condition, but also extends the life of the equipment attached to it.

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Dale Annoye

Dale Annoye

Dale has been with Crane Engineering as a Senior Application Engineer for 40 years. His experience in sanitary and industrial processes makes him the go-to guy for many of Crane Engineering's customers.

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