Expansion joints are designed to be an expendable component to a piping or ducting system. Premature failure of the integrity of an expansion joint can often be attributed to a few common oversights. Proper planning to avoid these oversights can extend the life of the expansion joint.

Design considerations

Maintaining a good line of communication with your manufacturer is an easy way to ensure you are getting the best expansion joint solution for your needs. When talking to your manufacturer be sure to give them all pertinent information about the service your expansion joint will experience. At Kadant Unaflex we have an acronym S.T.A.M.P. that covers many of the basic details needed to identify the correct type of expansion joint needed.

S - Size, the nominal ID of the pipe the expansion joint will be installed

T - Temperature, the internal and external temperatures required

A - Application, how much flexibility is required

M - Media, what is contained and the concentration if applicable

P - Pressure, what pressure is the media being transferred under

Installation errors

Proper installation is also critical to ensuring proper life of the expansion joint. Some common errors made during installation are installing with a reversed flow direction, shipping devices removed prematurely, and mechanical damage caused by work around the system. Installation with a reversed flow direction becomes more relevant when a flow liner or other device is installed to prevent debris from the media from accumulating in the convolutions. Rubber expansion joints may use a filled arch design to prevent build up with its arch.

Improper support

The supports in a piping system are very important to the system's stability. If inadequate support is not available, tie rods, control units, or other forms of support should be included in the expansion joint design.

Over pressurized

An expansion joint that is consistently under greater pressure than it was designed to allow will fail sooner than expected. Prevention of this failure goes back to communication with your manufacturer on what the system requires.

Chemical exposure

Chemicals such as acids and especially chlorides can cause problems internally in the system. Flushing the system with water after chlorides or other harsh chemicals are passed through the system is recommended to delay the onset of corrosion.  

Expansion joints, when used correctly, should give several years of service. Failures often are preventable with maintenance and correct usage. Kadant Unaflex’s team can work with you through the process to find the configuration that will best suit your expansion joint application.