Elbow Pressure Balanced Expansion Joints

An Elbow Pressure Balanced Expansion Joint is designed to absorb externally imposed axial movement without imposing pressure loading on the system. This is accomplished by using two bellows both at line pressure tied together and acting in opposite directions. It is used where pressure loading on piping or equipment is not acceptable.

To move the joint itself is not balanced. Both the flow bellows and balancing bellows must be compressed or elongated in operation and the combined axial spring force acts on the piping or equipment. Since the forces needed to move the bellows of these joints are of low magnitude these are usually not objectionable.

These elbow pressure balanced expansion joints are usually installed at change of direction. They may also be designed for in line operation. In case of single Elbow joints when it is subjected to both axial and lateral movements both the anchors at the end of the piping run and the one on the machine are intermediate anchors and only directional guiding is required. By proper design the guide directly above the equipment can be made to absorb the axial movement forces of the expansion joint without imposing these on the equipment. The only force imposed on the equipment is the force which is required to deflect the expansion joint.

Manufacturing this type of pipe expansion joint bellow is really a combination of several metal expansion joint types. The objective is to maintain and stabilize the pressure thrust so that main anchoring of the pipe or alongside equipment is not needed, forces and movements on attachment flanges of a gentle machine, like turbines, are kept to acceptably low levels. The deflections to be accepted are controlled by the proper type of flexible pipe expansion joint, which normally is a tied universal joint type to accept lateral movements. However, the pressure balanced elbow joint is usually required because axial deflections are also present. In order to accept these movements, a bellows is added beyond the elbow with the same cross-sectional area as the ones in the universal section.

  • Simple to manufacture
  • Stable at high pressures
  • Absorbs small amounts of axial and lateral movement
  • Eliminates change in pressure
  • No main anchors required
  • Conserves space
  • This balancing stainless steel bellow is joined by the tie rods to the pipe beyond the universal section; in this way, the pressure thrust is contained as tension in the tie rods. The segment of the flexible expansion joint between the tie rods, which includes the elbow, is now free to move axially, with the only resistance being a function of the spring rates of the bellows. Because of their pattern, however, the spring rate of the entire expansion joint is the sum of the spring rates of the balancing and the universal expansion joints bellows. This is a fixed volume system, in that when the universal end compresses, the balancing end extends the same amount.


  • Industrial piping systems
  • Elbow Pressure Balanced Expansion Joints Manufacturer In India

    + 91 - 70289 97949
    + 91 - 98904 54224
    + 91 - 98909 77244
    Address: Final plot no.38/1 Ramtekdi Industrial Estate, Hadapsar, Pune - 411013, Maharashtra, India