Knowledge Series:
Molded Spherical Joints with Floating Metal Flanges
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Molded Spherical Joints with Floating Metal Flanges: Introduction
• Included in this section:
• What is a molded spherical expansion joint with floating flanges?
• Molded Spherical Expansion Joint Design Configurations
• Common Applications for Molded Spherical Expansion Joints
• Advantages of Molded Spherical Expansion Joints
• Common Available Elastomers
• Installation Considerations
Molded Spherical Joints with Floating Metal Flanges
• What is a Molded Spherical Expansion Joint with Floating Metal Flanges?
• Molded spherical type expansion joints incorporate the movement and vibration dampening capability of spool type expansion joint joints into a compact and robust device.
• The distinguishing features of the molded spherical expansion joints joints are the shape of the body, floating flanges and the beaded seal.
• Design Notes:
• Spherical body shape
• Floating flanges
• Beaded seal with reinforcing cable
• Reinforcing plies
• Inner tube and outer cover can be different elastomers
Molded Spherical Joints with Floating Metal Flanges
• Typical spherical type expansion joint configurations:
• Single Sphere
• Double Sphere, for applications requiring greater movement than a single sphere
• Double Sphere Union, for smaller-sized threaded pipe applications
Molded Spherical Joints with Floating Metal Flanges
• Common Applications of Molded Spherical Joints:
• Applications requiring vibration or sound dampening
• Commonly installed as pump and equipment connectors to acoustically isolate rotating equipment from system piping
• Corrosive media applications not appropriate for metallic expansion joints
Molded Spherical Joints with Floating Metal Flanges
• Advantaged of Molded Spherical Joints with Floating Metal Flanges:
• Spheres are a very strong yet flexible expansion joint. The shape is inherently stronger than a spool type expansion joint, and results in uniform pressure distribution throughout the wall.
• Spherical joints have a distinct advantage over metallic expansion joints for corrosive applications and installations requiring a high cycle life.
• The contour prevents sediment accumulation and creates less turbulence and pressure drop than spool joints.
• The seal bead eliminates any requirement for gaskets between mating flanges.
Molded Spherical Joints with Floating Metal Flanges
• Common available Elastomers:
• EPDM
• Neoprene
• Butyl
• Nitrile
Molded Spherical Joints with Floating Metal Flanges
• Installation Considerations
• Don’t use expansion joints to compensate for pipe misalignments
• Tighten bolts to proper torque according to the manufacturer’s specifications
• Always include control units
• Check temperature and pressure limits against operating conditions
• Check material compatibility with medium in the pipes and environment of installation
• Follow the instructions!
For additional technical information regarding Molded Spherical Expansion Joints with Floating Metal Flanges as well as other rubber expansion joint designs consult the Fluid Sealing Associations Technical Handbook for Expansion Joints Piping (https://www.fluidsealing.com/)
