Why do we require an Expansion Joint ?

Any pipe connecting two points is subjected to numerous types of forces, which result in stresses on its wall.

    The basic causes of these stresses are:

  • Internal or External pressure at working temperature,
  • Frequent temperature or pressure changes,
  • Movement imposed on pipe section by external restraints, (Eg. the movement of equipment connected rigidly to the pipe),
  • Vibration of equipment or structure to which the pipe is connected,
  • Thermal expansion
Let us consider the stress due to the movement and thermal expansion. The stress on the wall of the piping is related to the force or movement exerted on it by external restraints.When either the values of the stresses or the values of the external forces or moments exceed the maximum allowable values, the flexibility of the pipe must be increased artificially.This can be done either by altering the layout of the pipe or by inserting high flexibility section into it.