TWDB for High Velocity Industrial Duct Systems

 Theremofit Wrap Around Duct Work for High Velocity Industrial Duct Work

Example of a Duct Joint sealed by TWDB

     Raychem (now called Covalence) make a product for sealing the joints on high velocity, industrial duct work.  It is called TWDB which is short for thermofit wraparound duct bands.  TWDB is a heat shrinkable tape for sealing duct joing on air conditioning and heating systems.  

     TWDB Duct Sealing Tape is a two layer system.  The first layer is a copolymer adhesive that bonds very well to metal duct work.  The second outer layer is a thick walled, radiation crosslinked, high density polytheylene.  TWDB is a hot applied duct sealing tape composed of a heat shrinkable backing with a heat resistant pressure sensitive, non-drip adhesive and a closure patch.  TWDB is superior to any cold applied options out there and dramatically easier to install (and less messy) than the paste options out there in the world today.

     Installed using propane torches or industrial heat guns, TWDB is very easy to install.  The ducts are assembled and raised into position.  The TWDB tape is wrapped around the ducts where joined and a closure is then applied, allowing the tape to essentially form a tube or band around the joint.  When heated to a temperature of 267F, the tape shrinks tightly around the substrate of the joint area.  During recovery, the adhesive softens and flows to form a tenacious bond with the substrate and to fill any irregularities such as the interlocking seams of the duct work.  The bond builds up during cool down and is fully retained after completion of the job.  Mechanically strong, pressure tight seals are created by the TWDB.

    Features of TWDB thermofit wrap around duct bands:

• No primer is required - leading to no dry time and a simple install.
• Low preheat sensitivity and proven functionality.  TWDB allows easy installation combined with high functional performance levels. 
• High mechanical resistance backing.  TWDB resists vibration in high velocity systems operating at up to 158F.
• Minimal inventory costs.  TWDB's cut to length packaging system eliminates the need for multiple sizes (all rolls are 165 feet long; you can choose 3" or 4" widths).
• Specialty formulated sealant ensures a reliable protection with high peel and shear values after installation.
• No special equipment or training required.
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TWDB Application Guidelines

 TWDB Installation Guidelines

     TWDB is a Covalence (formerly Raychem) product that has been around for many years.   TWDB stands for Thermofit Wraparound Duct Bands and these would be used to seal up the joints on high velocity industrial duct work to eradicate air leaks at those joints.  Available in 3" and 4" widths, TWDB is sold in rolls that are 165 feet long.  Installers would cut their own strips of material from those rolls (cut lengths are explained on the box) and the installation is simple, easy -- and maybe most importantly:  NOT MESSY!

Give me a call (936/321-3333) or shoot me an email for pricing (steve@jsicoatings.com)

Join duct sections that you will be sealing with TWDB using internal couplers or crimped end male/female type connections.  Apply sheet metal screws.  Two screws 180 degrees apart are usually sufficient.

Wipe the joint area to remove foreign materials.  Preheat joint to remove moisture and burn off any surface oil that may be present.  

Cut the TWDB (thermofit wraparound duct band) to the appropriate length.  Center the TWDB and wrap it around the duct joint (TWDB was once called TDAB)

Using the included supplied high temperature sealing tape (which holds the duct band in place during the shrink process), secure the loose TWDB end by taping in place.  TWDB should overlap onto itself. 

Using a standard propane torch, heat TWDB on all sides until it has shrunk uniformly and adhesive is showing at each end.  

Smooth down the overlap area with a gloved hand to ensure proper contact to the duct.