Proven Solution for Sealing Industrial Ductwork: Covalence TWDB

 

If you work with industrial HVAC and piping systems, chances are you’ve come across Covalence (formerly Raychem) TWDB. TWDB is a thermofit, wrap-around duct band specifically designed to create a pressure-tight seal on ductwork—helping ensure long-term system integrity even in challenging environments.

Engineered for reliability, TWDB delivers a durable seal that stands up to demanding conditions where traditional sealing methods often fall short. Once installed, it provides confidence that your ductwork will remain protected and leak-free over the long haul.

For ease of use in the field, TWDB is stocked in both 3" and 4" widths and supplied in a 165-foot continuous roll. Each roll is packaged in a purpose-built box that allows installers to quickly and accurately measure the required length before cutting, reducing waste and improving installation efficiency.

Installation is straightforward and familiar to most crews. TWDB can be applied using either a propane torch or an industrial heat gun, allowing it to conform tightly to the duct surface and activate the thermofit properties that make the seal so effective.

TWDB is not a new or unproven product—it has seen consistent use for decades across industrial applications. That longevity speaks to its performance, reliability, and the trust it has earned among contractors and maintenance professionals alike.

When long-term sealing performance matters, Covalence TWDB remains a simple, proven solution.

Thermo Fit Wrap Around Duct Band

Thermofit Wraparound Duct Band

 

     Duct work, is by its very nature, riddled with leaks and air paths.  Every joint where one bit of duct work connects with another allows a loss of pressure, air flow, temperature, gasses, etc.  Imagine trying to set up a sprinkler system in your yard, but for all of the PVC pipe, you don't bother using connectors, glue, epoxy or couplings...you just kind of slide one bit of PVC into another...and assume that will be good.

 

     Well that is exactly what happens with duct work in commercial and residential buildings all over the USA. Leaks, leaks and more leaks are leading to less energy efficient HVAC systems, less effective chemical hoods and more and more wasted dollars on lost heated or cooled air flow. 

 

     So what is the answer?  Using a product like our TWDB heat shrinkable tape for sealing joints on duct work.  TWDB is installed using a propane torch or an industrial heat gun.  The TWDB covers the seam at the joint of the duct work and overlaps onto the adjacent duct.  It forms an air tight seal preventing any air current leakage.  You are paying to get a certain amount of air from point A to point B.  Why are you allowing 20+% of that air to escape along the path??

 

     TWDB is also used to seal the vent work on chemical fume hoods.  It makes sure any vapors or gasses get exactly where you want them to go without allowing them to escape where they shouldn't go.  Sounds smart huh?  So, get your HVAC situation under control.  Improve the efficiency of your HVAC system.  Reduce your energy bills!  Stop heating or cooling the attics and ceilings of your buildings!

Thermofit Wraparound Heat Shrink Duct Bands (TWDB*)

Thermofit Wraparound Heat Shrink Duct Bands (TWDB*) 

Heat-shrinkable tape for sealing duct joints on round air conditioning
or heating systems.

 Product Description: TWDB duct joint sealing tape (band).

• Construction: Two-layer system
• First Layer: Copolymer adhesive.
• Second Layer: Thick-walled, radiation-cross-linked, high density polyethylene

TWDB is a hot applied duct sealing tape composed of heat-shrinkable backing with a heat
resistant pressure sensitive, non-drip adhesive and a closure patch.

TWDB is installed using propane gas torches. The ducts are assembled and raised into position after installation. The tape is wrapped around the ducts where joined, a closure is then applied, allowing the tape to essentially form a tube or band around the joint. When heated in excess of 120°C (250°F), 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 the irregularities such as the interlocking seams. The bond strength builds up during cool down and is fully retained after completion of the job. Mechanically
strong, pressure tight seals are provided.

Note: TWDB is not intended to be used in industrial environments where organic solvents, oil or chemicals are present.

Product Features/Benefits:

• No primer required allowing for no drying time and easy application.
• Low preheat sensitivity & proven functionality allows easy application combined with high functional performance.
• High mechanical resistance backing; TWDB resists to vibration in high velocity systems operating
  up to 70°C (158°F).
• Minimal inventory cost. TWDB’s cut-to-length system eliminates the need for multiple sizes.
• Specially formulated sealant ensures a reliable protection. Provides high peel and shear values after installation.
• No special equipment or skills required which makes installation fast and easy while keeping installation cost low.

Product Selection Guide:

Max. operating temperature: 70°C (158°F)
Compatible line coatings:  Jointing galvanized ducts
Min. preheat temperature: Remove moisture + surface oil
Recommended pipe preparation:  ST3

TWDB type products are available as a roll

Thermofit Wraparound Duct Tape Ordering Sizes Include:

A roll length of 165 ft with a sleeve width of 2 inches

A roll length of 165 ft with a sleeve width of 3 inches

A roll length of 165 ft with a sleeve width of 4 inches

• closure patches included

                                                                                                                                                                      

Install TWDB on rectangular and flat oval duct following the 
procedures for round duct with the following additional step:
Immediately after shrinking is complete, press down the still 
hot TWDB with roller or gloved hand on flat sections.

*See install guide for prior steps.