Case story


Biomass Power Plant


EN 13445

These 2-meter-long Pressure Balanced Expansion Joints were installed at the steam turbines in a Croatian biomass cogeneration plant.


Relieving loads on the turbines
Pressure Balanced Expansion Joints are designed to absorb movements from a pipe system. They can accommodate axial and lateral movements where due to structural or economic considerations the anchoring of the pipe system is difficult or impractical. Pressure Balanced Expansion Joints do not transfer the internal pressure thrust onto to the fix points, adjacent equipment, or structures. In many cases only guides are needed to convert thermal expansion into a controlled movement, with fix points rarely required.
For this reason, Pressure Balanced Expansion Joints can deliver significant advantages. Particularly in such instances where pipe systems are connected to turbines, pumps, valves or other equipment, which are unable to withstand pressure thrust loads. Although Pressure Balanced Expansion Joints eliminate pressure thrust, it’s important to note that the existing load on the surrounding equipment is the total sum of the spring rates of both the flow Bellows and Balancing Bellows. The movement absorbed by a Pressure Balanced Expansion Joint should be understood as follows: if the thermal movement in the connected pipe is 20 mm, the flow Bellows of the pressure balanced unit will contract by 20 mm and the Balancing Bellows, with twice the effective area of the flow Bellows, will expand by 20 mm.


The advantage of a Pressure Balanced Expansion Joint lies with its capability to reduce the complexity and size of fix points by eliminating the pressure thrust, thereby delivering stability to the pipe system. This also reduces the required space for structures that carry fix points and guides. Pipe engineers are often challenged by space limitations due to the surrounding environment. Under such conditions it may not be possible to incorporate a number of fix points and guides that are normally required at high pressures. The Pressure Balanced Expansion Joint is the optimum solution for additional scenarios such as a short pipe run connecting two vessels, which are unable to withstand the pressure thrust loads. It can also provide a good solution for pipe systems at elevated heights, where additional supporting structures would significantly increase costs.


Pressure balanced design options
Pressure balanced expansion joints can be designed for any specific requirement with tie rods, cover and also for the absorption of lateral and/or angular movements (universal type).


The Pressure Balanced Expansion Joints for biomass power plant have the following design parameters:
Dimension: DN 600 • Installation length: 2003 mm • Medium: Steam 2,2% condensate • Design pressure: -1/3 barg • Design temperature: -10°C/250°C • AX: +/-20 mm • LA: +/-10 mm • Bellow: 1.4541 • Flanges and welding ends: 1.0425 • Inner sleeves: 1.4541


  • Suitable solution for the application
  •  Reliability of the Expansion Joint designed to work under the operating parameters
  • Reduces the complexity and size of fix points
  • Guaranteed to deliver safe, reliable and smooth operation.
  • Benefit from the considerable know-how of an experienced manufacturer

TECHNICAL information

  • Technical information on Pressure Balanced Expansion Joints is available in the Expansion Joint Catalogue
    page 359
  • Installation examples of Pressure Balanced Expansion Joints are available in the Expansion Joint Catalogue
    page 79 – 85


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Finger Type Expansion Joint with ring reinforcement for high pressure in a chemical plant.


This 4-meter long DN 2500 Inline Pressure Balanced Expansion Joint having a balancing bellow of DN 3800.


This design avoids closed spaces were the media could pack up and restrict the correct functioning of the bellows.