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 - Joint Specialists

TWDB Themofit Wraparound Duct Bands

     Thermofit Wraparound Duct Bands are heat shrinkable tapes, made of cross linked polyolefin, precoated with a hotmelt adhesive.  The band is cut to length on on the jobsite, wrapped around the duct joint and fixed at the overlap with a pressure sensitive adhesive patch.  TWDB is black in color in terms of the backing and also black in color with regard to the adhesive.  This is a product that shrinks at 125C which can be achieved with an open flame or with an industrial hot air gun.

     The typical application for this product is as a pressure sealing joint on round or flat oval ducts in air conditioning or heating systems.  TWDB can be used at up to 70C and pressures up to 50 kPa at 25C.  It is highly recommended for spiral ducting in high velocity air conditioning. 

     TWDB is available in standard widths of 3" and 4".  All rolls are 165 feet long and shipped within boxes can aid with measuring as each TWDB strip is cut.  The backing wall thickness is a nominal .5mm.  The adhesive coating thickness is a nominal .7mm.  This product is manufactured to shrink 15% which is significantly less than most of our heat shrinkable pipeline coatings which can range anywhere from 25% to 66%.

     Each TWDB roll is packed in a unique box, containing TWDB and a roll of positioning patches.  Installation instructions and recommended cut lengths are printed on the box.  Generally, the 3" wide TWDB will include 35 of the pressure sensitive closing patches.  The 4" wide will generally include 20 of the closing tape patches. 

     For the most part, the 3" TWDB is recommended for duct sizes of 400-800mm.  The 4" TWDB is recommended for duct sizes larger than that.  There really is no limit though.  The 4" TWDB could be used on any size duct offering even more overlap onto the adjacent ductwork.

     Feel free to contact us today for price and delivery information on your TWDB needs.  We can be reached Monday thru Friday at 936/321-3333 -- or around the clock (within reason) at steve@jsicoatings.com