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Thursday, June 19, 2025

TWDB - Thermofit Wraparound Duct Bands

 TWDB – Thermofit Wrap Around Duct Bands

 are advanced, heat-shrinkable sealing solutions designed for joining and sealing ductwork in HVAC and industrial piping systems. These bands are engineered to provide reliable, pressure-tight, and durable seals for round air conditioning or heating ducts, ensuring long-term system integrity in challenging environments.


TWDB duct bands are constructed as a two-layer system:

  • : Copolymer adhesive that is heat-resistant and pressure-sensitive, ensuring a strong bond to the duct surface.

  • : Thick-walled, radiation cross-linked, high-density polyethylene, providing robust mechanical protection and durability.

The bands are supplied with a closure patch and are typically installed using propane gas torches. After wrapping the band around the duct joint and applying the closure, heat is applied. The band shrinks tightly around the joint, and the adhesive flows to fill any irregularities, such as interlocking seams, forming a seamless, pressure-tight seal.


  • : The system eliminates the need for primers or drying time, allowing for quick and easy installation.

  • : TWDB bands perform reliably even with minimal preheating, reducing installation complexity.

  • : The polyethylene backing provides exceptional resistance to mechanical damage, abrasion, and environmental stress.

  • : The adhesive flows during installation, filling gaps and creating a strong, pressure-resistant barrier.

  • : Suitable for jointing galvanized ducts and compatible with a variety of line coatings.

  • : The bond strength increases as the material cools, ensuring lasting performance after installation.


PropertyValue
Max Operating Temp70°C (158°F)
Tensile Strength3000 psi
Hardness55
Shrink Force40 psi
Dielectric Strength680 volts/mil
Softening Point120°C (248°F)
Shear Strength750 psi
Installation Temp>120°C (250°F)

  1. : Clean the duct joint area (recommended preparation: ST3).

  2. : Wrap the TWDB band around the joint and apply the closure patch.

  3. : Use a propane torch to heat the band above 120°C (250°F).

  4. : As the band shrinks, the adhesive softens and flows, filling gaps and bonding to the substrate.

  5. : Allow the assembly to cool, resulting in a mechanically strong, pressure-tight seal.


  • Sealing joints in round air conditioning or heating ducts.

  • Ensuring airtight and watertight seals in HVAC systems.

  • Industrial piping systems requiring robust, long-lasting duct joint protection.


FeatureDescription
ConstructionHeat-shrinkable, two-layer wraparound band
AdhesiveCopolymer, heat-resistant, pressure-sensitive
BackingHigh-density, cross-linked polyethylene
Operating TemperatureUp to 70°C (158°F)
ApplicationHVAC, industrial duct sealing
InstallationNo primer, torch-applied, easy to use
Seal QualityPressure-tight, durable, mechanical strength

 offer a reliable, efficient, and easy-to-install solution for duct joint sealing, combining advanced materials with proven installation performance for demanding environments.

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