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Showing posts with label duct bands. Show all posts
Showing posts with label duct bands. Show all posts

Friday, February 6, 2026

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.

Friday, June 2, 2023

Duct Band Sealing

TWDB Thermofit Wraparound Duct Band: Efficient Sealing Solution for Air Conditioning Systems

Introduction: When it comes to maintaining efficient and reliable air conditioning and heating systems, proper sealing of duct joints is essential. TWDB Thermofit Wraparound Duct Band offers a comprehensive solution for sealing duct joints in round air conditioning or heating systems. This heat-shrinkable tape provides a secure and long-lasting seal, ensuring optimal performance and energy efficiency. In this article, we will explore the features, benefits, and applications of TWDB, highlighting its role in improving HVAC system performance.

Product Description: TWDB is a two-layer system comprising a copolymer adhesive as the first layer and a thick-walled, radiation-cross-linked, high-density polyethylene as the second layer. This construction ensures a robust and reliable sealing solution for duct joints. The tape is heat-shrinkable, allowing it to tightly wrap around the ducts when heated above 120°C (250°F). The adhesive softens and forms a tenacious bond with the substrate during recovery, filling irregularities and interlocking seams. The resulting mechanically strong and pressure-tight seals provide optimal airflow control and prevent energy loss.

Easy Installation and Application: TWDB offers a user-friendly installation process. Propane gas torches are used to heat the tape and facilitate shrinkage. After assembly and raising the ducts into position, the tape is wrapped around the joint area, and a closure patch is applied, effectively forming a tube or band around the joint. The tape's unique properties ensure a tight seal and a reliable bond, which strengthens during cool down and remains intact after completion of the job. This simple installation process saves time and effort, reducing overall installation costs.

Features and Benefits:

  1. No primer required: TWDB eliminates the need for primers, reducing drying time and making the application process quicker and more convenient.
  2. Low preheat sensitivity & proven functionality: The tape's low preheat sensitivity allows for easy application while maintaining high functional performance, ensuring reliable sealing.
  3. High mechanical resistance backing: TWDB's design enables resistance to vibrations in high-velocity systems operating at temperatures up to 70°C (158°F), ensuring long-term durability.
  4. Minimal inventory cost: The cut-to-length system of TWDB eliminates the need for multiple sizes, reducing inventory costs and streamlining the ordering process.
  5. Specially formulated sealant: TWDB employs a specially formulated sealant that provides reliable protection, ensuring high peel and shear values after installation.
  6. No special equipment or skills required: With no need for specialized equipment or skills, TWDB's installation is fast and easy, reducing labor costs.

Product Properties: TWDB's physical properties make it a reliable choice for duct joint sealing:

  • Backing Tensile strength: 3000 psi (20 MPa)
  • Ultimate Elongation: 580%
  • Hardness, Shore D: 55
  • Shrink force at 150°C (302°F): 40 psi
  • Dielectric strength: 680 volts/mil (27 kV/mm)
  • Water absorption: 0.05%

System Requirements: TWDB meets various system requirements, ensuring optimal performance:

  • Max. operating temperature: 70°C (158°F)
  • Compatible line coatings: Jointing galvanized ducts
  • Min. preheat temperature: Remove moisture + surface oil
  • Recommended pipe preparation: ST3
  • Soil stress restrictions: Not applicable

Conclusion: TWDB Thermofit Wraparound Duct Band offers a highly effective solution for sealing duct joints in round air conditioning or heating systems. Its heat-shrinkable tape, combined with a pressure-sensitive adhesive and closure patch, creates a secure and durable seal. With easy installation, minimal inventory costs, and excellent sealing capabilities, TWDB will practically pay for itself.

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 steve@jsicoatings.com