STEAM TURBINE
FLEXIBLE JOINTS WITH HINGES

Belman engineered and manufactured three Flexible Joints with hinges for installation in the pipework at a steam turbine in an Austrian CHP plant.

 

CLIENT ISSUES – Special requirements for the steam turbine Flexible Joints
Because the steam turbine generates thermal movements, the client needed the pipework to have Flexible Joints to absorb these movement in the steam piping system. The Design data for the two Angular Expansion Joints should be different from the design data for the Lateral Expansion Joint. The two Angular Expansion Joints needed to be combined in one unit allowing for lateral movement as well. The client was looking for help in designing and manufacturing Expansion Joints with these particular requirements.

 

BELMAN SOLUTION – Angular/Lateral Flexible Joints with Hinges
Belman designed the Expansion Joints to meet the specifications and layout requirements of the client. The solution therefore called for two different Expansion Joint designs, these being (1) a double bellow Hinged Lateral Flexible Joint, which could take up the +/-50 mm (range 100 mm) lateral movement. The benefit of using hinges is that they can control the loads on adjacent pipe system (i.e. no pressure thrust), restrict the Expansion Joint to solely lateral movement and ensure equal load on the bellows. A double bellow Expansion Joint, like this one, can absorb larger lateral movements than a single bellow. (2) The other required Flexible Joint solution was two single bellow Angular Flexible Joints with hinges to take up +/-2° angular movement combined in one unit by inserting a middle pipe allowing the Flexible Joint to take up +/-4° angular movement. The benefit of using hinges here is that Expansion Joints with hinges allow angular movement in a single plane with the pressure thrust forces being restrained within the unit.

 

Another advantage of using hinges is that they prevent the bellows from axial deflection. As Hinged Flexible Joints are fully restrained, they only require inexpensive guides and/ or light fix points. This gives an economic advantage when working with larger diameter, hot piping systems, even if the movements are complex and in several planes. Depending on the design, Hinged Flexible Joints can absorb either lateral or angular movement. When designing Expansion Joints with hinges, it is important to be aware of any surrounding external hardware or pipes. This is because the hinges need sufficient installation space as well as movement clearance when in operation.

 

Protective coating system
The steam turbine Flexible Joints with hinges were coated with Jotun Solvavitt – a single-component, physically drying silicone acrylic coating that is heat-resistant. The Expansion Joints were also tested and CE marked.

 

Belman – expertise in Hinged Flexible Joints
Through the years, Belman have supplied numerous Flexible Joints with hinges in a large range of sizes and in a wide range of materials. Belman is known for its ability to engineer high-end Expansion Joint solutions tailored to the piping layout needs and requirements of its clients. Read more about Hinged Expansion Joint solutions here:
Angular Flexible Joints with hinges
Lateral Flexible Joints with Hinges