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Stainless steel


These 4 Pressure Balanced Expansion Joints made entirely from stainless steel were designed and manufactured for a chemical plant, producing plastic, in Northern Europe.

The design
The pressure balanced expansion joint is due to the media and surrounding areas made completely from stainless steel. The media is a mix containing among others phenol, acetone, water etc. The tie rods are galvanized, but aside from them, everything else is made from stainless steel. The expansion joints are mounted with external limiters. As the Pressure Balanced Expansion Joints are to absorb both axial and lateral movements a construction with internal limiters were not an option. Also 4 pcs. DN 350 Lateral Expansion Joints were part of this project, and they will be placed on other locations in the pipeline.

Absorb both axial and lateral movements
The design of the Pressure Balanced Expansion Joints are among given by the movements they are to absorb. Pressure Balanced Expansion Joints can accommodate axial and lateral movements where anchoring of the chemical plant’s pipe system is difficult or impractical due to structural or economic considerations. For this project they are to absorb both lateral and axial movements, and for that reason, they are designed with two flow bellows and one balancing bellow. As the lateral movements are not that big an additional flow bellow and a middle pipe is not needed. As the Pressure Balanced Expansion Joints are to operate under full vacuum extra bolts are placed on the limiters on both sides of the flanges.

Advantages by use of pressure balanced expansion joints
Selection of Pressure Balanced Expansion Joints in general, and for this project, can offer significant advantages. Pressure Balanced Expansion Joints are often a space saving solutions. Fix points are usually not required, only guides can ensure the turning of the thermal expansion into a controlled movement. Furthermore, they reduce size and complexity on fix points and guides. Even the need for hangers can be reduced as the Pressure Balanced Expansion Joints balance the pipeline. Further to that this type reduce the external loads on connected equipment as Pressure Balanced Expansion Joints do not transfer the internal pressure thrust onto the fix points, adjacent equipment, or structures of the chemical plant.

Design parameters of the Pressure Balanced Expansion Joints
The Pressure Balanced Expansion Joint has the following design parameters:
Quantity: 4 pcs • Dimension: DN 500 • Length: 845 mm • Design temperature: 195°C • Design pressure: -1/3,5 barG • AX: +5/-20 mm • LA: +/-2 mm • Bellows: 1.4404 • Flanges: 1.4404 • Inner sleeves: 1.4404