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How to Measure a Rubber Expansion Joint

Heating and cooling causes many materials to expand and contract, often with a noticeable effect. This expansion and contraction can cause damage to a system; for instance, if a pipe system in a factory transporting hot materials were to expand too much, it could crack the pipes. Rubber expansion joints are flexible pieces that allow materials, like pipes, to expand and contract safely without damage. When these joints tear or deteriorate, you need to measure for a new joint.

Things You'll Need

Ruler

Instructions

- 1
  Allow the system to cool to a normal ambient temperature. This allows the pipes to reach their normal length for proper measuring. The system should be turned off, any pipes depressurized and any fluids removed from the pipe before doing maintenance.
- 2
  Remove the bad joint and inspect the area for problems, such as dirt, sharp edges, or misaligned mating flanges. Mating flanges are the plates on the pipes that attach to the joint flanges and hold the expansion joint in place.
- 3
  Clean the mating flanges and fix any problems, especially alignment problems, before measuring. The mating flanges should have no more than 1/8 inch of misalignment.
- 4
  Measure the distance between the face plates of the two mating flanges, or the amount of space between them. You can use an ordinary ruler, though more accuracy is better. Measure in several places around the plates; this will help ensure that the plates are aligned properly, as well. Your measurements will help you to purchase a suitably sized replacement.

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