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Tuesday, June 23, 2015

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

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