Fabric Expansion Joints for High Temp Flue Ducts

fabric expansion Joints ThermaFlex Fabric Expansion Joints are non-metallic flue duct expansion joints that provide stress relief for piping and ducting systems by absorbing thermal growth and shock, isolating mechanical vibration, and allowing for misalignments.ThermaFlex expansion joints are precision engineered specifically for your application.

ThermaFlex Flue duct expansion jointsare custom engineered to handle low pressure (┬▒3 psig) applications with temperatures ranging from -100°F to more than 2000°F. Industry Proven materials and precise engineering go into every Thermaflex Fabric Expansion joint.

UNAFLEX® is the country's leading Expansion Joint Manufacturer. Since 1972, Unaflex® has been dedicated to state-of-the-art technologies combined with industry proven processes. Unaflex® has become the industry leader in "Combined Technologies" for the Expansion Joint and Flexible Hose industries.

UNAFLEX® is a full-service Engineering and Manufacturing Company dedicated to providing flexible solutions. Our capabilities include:

  • Metal, Fabric and PTFE Expansion Joint Manufacturing
  • Laboratory testing, analysis and field service.

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Service Features of Fabric Expansion Joints

  • Absorb axial, transverse and torsional movements
  • Corrosion and chemical resistance
  • Negligible spring rates and loads
  • Easily repairable and installable
  • High cycle life
  • Unique application solutions
  • Vibration dampening and sound attenuation
  • More movement in shorter face-to-face
  • Less force to flex than metal expansion joints
  • Excellent corrosion and chemical resistance
  • Temperature capability range (-110°F to more than 2,000°F)
  • Lower shipping and installation costs
  • Variety of flexible belt materials available:
    • Single-layer and composite belts
    • Elastomers have excellent abrasion resistance
    • Custom designed for each specific application

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Design Considerations

  • Media: Internal and External Environment
  • Temperature: Constant operating and maximum excursion
  • Pressure: Normal positive or negative
  • Movements: Axial and lateral, simultaneously or independently
  • Installation: Existing equipment and duct flanges
  • Assembly: Factory-assembled or field-spliced


Baffles are usually not necessary with elastomeric expansion joints due to the tube resistance to most abrasive particular matter. However, baffles must be used with fabric composite joints to protect the inner surface form particulates in the gas stream. UNAFLEX® can supply baffles fabricated from carbon steel, stainless steel, or other materials as required.

Retaining Rings

Standard construction calls for 2" wide, 3/8" thick bars with slotted holes for easy installation. Material of construction can be carbon steel, corten or stainless steel.


  • U-type
  • Belt type
  • Square
  • Rectangular or round
  • No size restriction
  • Choice of FF dimension, depending on movements
  • Associated Metal Work: Backup bars, frames, flanges and baffles

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