by FSA Member Lloyd Aanonsen
December 17, 2011

Compensates for Misalignment

It is common in both new construction and replacement applications to encounter pipe misalignment. Minor misalignment can be corrected with standard expansion joints, and custom units can be fabricated with large permanent offsets. The custom fit units are easier to install and will have a longer, maintenance-free life.

Large pipe misalignment
Figure 3. Large pipe misalignment


Provides Access to Piping and Equipment

Access to piping and equipment can be easily achieved by treating the rubber expansion joint as a removable spool piece. If a self retracting design is needed, a dismantling joint can be used. This is another example of system difficulties that may arise without the use of rubber expansion joints.


Rubber expansion joints have numerous design advantages—including their enhanced construction and expansive application capabilities. They should not be viewed as the weak link in the piping system. Instead, they are a functional component that has little or no alternative replacements.

In addition, expansion joints can adapt to misalignment that is often found in modular construction. Ultimately, the use of rubber expansion joints is imperative for a successful operation on all functional levels. Although stress analyses can ensure proper pipe design codes, expansion joints safely accommodate variables and contingencies and enhance the system's overall reliability and performance.

Quantifying and incorporating these design advantages into useful data bases will ultimately enhance the pipe stress analysis program and its applications.

Pumps & Systems, December 2010

Fluid Sealing Association 

"Sealing Sense" is produced by the Fluid Sealing Association as part of our commitment to industry consensus technical education for pump users, contractors, distributors, OEMs, and reps. As a source of technical information on sealing systems and devices, and in cooperation with the European Sealing Association, the FSA also supports development of harmonized standards in all areas of fluid sealing technology. The education is provided in the public interest to enable a balanced assessment of the most effective solutions to pump systems technology issues on rational Total Life Cycle Cost principles.

The Piping Systems Non-Metallic Expansion Joint division of the FSA is one of six with a specific product technology focus. As part of their mission they develop publications such as the newly revised seventh edition Technical Handbook Non-Metallic Expansion Joints and Flexible Pipe Connectors and the Non-Metallic Piping Expansion Joint Installation Guide. The former provides construction, installation, and application details while the latter is a “hands-on” simplified guide for maintenance operators and engineers.  Both are primers intended to complement manufacturer's documents produced by the member companies.   In addition, standards such as FSA-PEJ-701-06 Piping Systems Non-Metallic Expansion Joint Hydrotesting and Vacuum Testing, FSA-PEJ-702-06 Rubber Flanged Non-Metallic Expansion Joint Installation, Maintenance, and Storage, and FSA-NMEJ-703-99 Specifications of Elastomers Used in Piping Systems Non-Metallic Expansion Joints have been developed in response to important user issues.

Following members of the Piping Systems Non-Metallic Expansion Joint division sponsor this "Sealing Sense" series:

  • Bachmann Dampjoint, Inc.
  • Daikin America, Inc.
  • Dinatecnica Ind. E Com.
  • DuPont Performance Elastomers L.L.C.
  • 3M Dyneon
  • Garlock Sealing Technologies
  • General Rubber Corp.
  • KE-Burgmann A/S
  • Meccom Industrial Products Co.
  • Mercer Rubber Company
  • The Metraflex Co.
  • Proco Products, Inc.
  • Solvay Solexis, Inc.
  • Unaflex Incorporated